No, if I was playing 1e, I'd be either dead or an immortal myself.
Remember that in 1e, time between adventures passed in real time (i.e., real time between gaming sessions). So for 3,067 years to pass in game time either the bulk of that had to pass while I was at the table actually adventuring, in which case I'd be FAR beyond 9th level, or else I'd be dead.
Instead, my suggestion is that Gandalf does only a few things interesting between the end of
The Rings of Power and the start of
An Unexpected Journey. Sure, he did a lot of wandering and a lot of researching and a lot of adventuring, but they weren't high XP adventures. Tolkien's world is pretty low-magic for PC-power, so while Gandalf defintely should be an experienced adventurer alongside 1st-3rd level Dwarf Fighters and a 1st level Halfling Expert or Rogue (depending on whether Bilbo is a PC or a hireling/companion), I don't think he'd be much higher tiers yet. Meanwhile by the time he fights the Ringwraiths and the Balrog in LotR, he's clearly much higher level. He gained a lot of levels from his solo-adventurer in Dol Guldur and from all the orcs he killed in the Battle of the Five Armies…