The 1960's book for
Spycraft has been mentioned, but I should also point out 'The Hand of Glory' for
Spycraft. While it's set in the present, it's all about two-fisted action against occult nazis hunting for ancient mystic relics. It's got half-tracks in it
. It also has the explorer class, which is definite Indian Jones-in' for
Spycraft 
. Here's the first 5 levels (it's a 20-level base class).
- - -
Explorer
Whether in the steaming rainforests of Borneo or the concrete jungle of downtown New York, some agents cannot resist the call of discovery. Many organizations field agents who circle the globe in search of places and phenomena beneath the notice of their technological colleagues. These individuals bring a wealth of experience with exotic locations to any team, as well as a steady hand in the face of bizarre circumstances.
Abilities: Most explorers fancy a bit of rough and tumble, so decent Strength and Dexterity can be very helpful. The most pressing ability for any explorer, however, is unquestionably Intelligence, the source of wits he stakes his life upon during every mission.
Vitality: 1d10 plus Con modifier per level.
Class Skills
The explorer’s class skills and key abilities are:
Class Skill (Key Ability)
Balance (Dex)
Boating (Dex)
Climb (Str)
Cryptography (Int)
Cultures (Wis)
Drive (Dex)
First Aid (Wis)
Gather Information (Cha)
Handle Animals (Cha)
Jump (Str)
Knowledge (Int)
Languages (Int)
Listen (Wis)
Mechanics (Int)
Open Locks (Dex)
Search (Int)
Spot (Wis)
Survival (Wis)
Swim (Str)
Tumble (Dex)
Skill Points at 1st level: (6 + Int modifier) x 4.
Skill Points at Each Additional Level: 6 + Int modifier.
Class Features
The following are class features of the explorer.
Starting Feats: The explorer begins play with the following feats.
Armor Group Proficiency (Light)
Weapon Group Proficiency (Melee)
Weapon Group Proficiency (Pistol)
Connected: An explorer comes to know a wide variety of people through his travels. Once per session, he may spend an action die to seek out an individual with whom he has dealt positively in the past. Seeking this acquaintance out requires 1d6 hours. The acquaintance has one skill of the agent’s choice with a number of ranks equal to one-half the sum of the agent’s level + his Charisma modifier (rounded up).
Unlike allies gained through the faceman’s backup ability (see the Spycraft Espionage Handbook, page 23), the explorer’s acquaintance is only considered friendly (rather than helpful) and must be compensated for any services rendered.
The explorer may use this ability even in remote locations, so long as there are at least 40 people within a 25-mile radius around the explorer when he declares the ability use (e.g. an Antarctic research base near the South Pole or a nomad camp in the midst of a desert).
This is the explorer’s core ability.
All Over the World: The explorer never ceases to wander the globe, honing his skills and nosing around in new places. At 1st level, he gains the World Traveler feat. All prerequisites for this feat — including minimum skill ranks and agent level — are waived.
Direction Sense: At 1st level, the explorer receives a +2 bonus with any roll to navigate from place to place, regardless of the skill being used. This bonus also applies when performing the “Shortcut” maneuver as a predator in a chase (see the Spycraft Espionage Handbook, page 188). This bonus increases by +1 at 4th level and by an additional +1 every four levels thereafter.
Bookworm: The explorer has unparalleled research skills and can frequently just ‘walk up to the right part of any library’ or ‘flip open a book to the right page’ with spooky accuracy. Starting at 2nd level, the explorer may reduce the amount of time required to conduct any research — whether using books, a computer, or other means. This ability may only affect researches that would otherwise take 10 minutes or longer. At 2nd level, this ability divides the research time required in half (rounded up).
Bonus Feat: At 3rd level and 5th level, the explorer receives a bonus feat from either the basic combat or fringe feat trees. (The Fringe feat tree was introduced in the Archer Foundation Chamber Book.) He must still meet all prerequisites for the feat, including minimum ability scores and base attack bonuses.
Uncanny Dodge: Starting at 4th level, the explorer gains the ability to react to danger before his senses would normally permit him to become aware of it. He retains his Dexterity bonus to Defense (if any) when flat-footed or being attacked by an invisible adversary (though he still loses his Dexterity bonus to Defense if immobilized).
This ability is identical to the uncanny dodge ability possessed by the fixer, and a multi-classed agent may add his explorer and fixer levels together to determine the effectiveness of this ability (though he may only gain the ability once).
The Explorer
Code:
Base Fort Ref Will Def Init Budg Gadg
Lvl Att Save Save Save Bon Bon Pts Pts Special
1 +0 +1 +2 +1 +1 +1 1 0 All over the world, connected,
direction sense +2, starting feats
2 +1 +2 +3 +2 +1 +2 2 1 Bookworm (1/2 time)
3 +2 +2 +3 +2 +2 +3 3 1 Bonus feat
4 +3 +2 +4 +2 +2 +3 4 2 Direction sense +3,
uncanny dodge (Dex bonus)
5 +3 +3 +4 +3 +3 +4 5 2 Bonus feat
Hope this helps
,
). I've also played a pulpish Call of Cthulhu game using the Chaosium BRP rules (which was very easy to do). After all, a pulp game is usually more a question of attitude and style than rules (as long as said rules allow you the option of high-adventure action - otherwise you are using the wrong system 
The 2nd edition printing will have d20 conversions notes. One of the mini-campaigns, in the main rule book, is called "Mein Zombie" - Nazi zombies in WWII (just to bring this post back on subject - sorta 
