All that sounds right. In fact, I think water dependent along with aquatic/amphibious makes sense.
For ability scores, probably average to low Dex (AC 9 suggests a -1 penalty to go along with its +2 size bonus), average to low Str, average Con, and reptilian mental scores (Int 1, Wis 12, Cha 2).
Perhaps Str 6, Dex 7, Con 11, Int 1, Wis 12, Cha 2?
Given the original's description and the conversion's organisation I vote for doing a Yphoz swarm when the individual creature is done
Regards
Mortis
They are composed of a gelatinous substance that matches the color of the water in which they live, ranging from black to varying shades of brown to varying shades of green or yellow. They may even be colorless. This feature makes them almost impossible to detect in their home pool (PCs in yphoz-infested water rolling 4 or less on 1d6 are surprised).
Their bodies excrete a sticky slime that helps them adhere to walls and ceilings. This slime will dry to a gummy substance on walls, floors, and ceilings, and a cave inhabited by a large number of yphoz will aquire [sic] a build-up of this elastic, gummy substance over time.
They also possess two long, whip-like tentacles.
Once it contacts something solid, it will swim in that direction and begin wrapping its tentacles around the victim. Should the victim start to swim in another direction, the yphoz can follow, towing itself on its unsuspecting meal.
The gummy substance excreted by the yphoz will adhere to a victim even underwater, and contains a numbing contact poison. While the poison will not kill a victim, the numbness can cause a victim to lose muscle control, and if swimming, the victim could potentially drown. One yphoz can cause one limb or torso to become numb and useless in 3 rounds. Three yphoz can cause one limb to become numb and useless in one round. A victim may make a saving throw vs. poison to avoid these effects. The victim must save once per round for each yphoz it contacts. Once all yphoz are removed from the victim, the poison will wear off and the limb will function normally after 4-6 turns. If a victim's head is touched by a yphoz, the victim will fall unconscious after six unsuccessful saves (e.g. six yphoz contact it in one round, or one yphoz contacts it for six rounds, etc.).
When a yphoz hits a victim, the DM should roll 1d6 to determine which part of the victim's body was hit: 1-head, 2-right arm, 3-left arm, 4-torso, 5-right leg, 5-left leg [sic].
When a specific body part takes damage, you can apply a -2 penalty to any action that the character undertakes using that portion of his body. For example, if a character's fingers get slashed, he makes attack rolls with a weapon in that hand at -2, he takes a -2 check penalty on Climb, Open Lock, Disable Device, Forgery, etc.
Head = Climb, Craft, Disable Device, Escape Artist, Forgery, Alchemy, Heal, Open Lock, Pick Pocket, and Use Rope checks; attack rolls.
Arm = Climb and Swim checks; attack rolls; Strength checks.
One eye= Spot, Search, Appraise, Alchemy, Forgery, Decipher Script, Open Lock, Disable Device, Craft, Read Lips, Scry, Sense Motive and Spellcraft checks; Wilderness Lore checks (for tracking); initiative checks; Dexterity checks; Reflex saving throws; Severe damage to both eyes blinds a character.
One Ear = Listen checks; initiative checks; Severe damage to both ears deafens a character.
Foot/Leg = Climb, Swim, Jump, Ride, Tumble, Balance, and Move Silently checks; Dexterity checks; Reflex saving throws.