you actually didnt build a motor though. you bought and installed a motor. what you are doing is "building" a car i guess, but that has nothing to do with replacing the blown motor.
honestly, i have no clue who either of you are but you kind of make yourself look bad by calling people out...
i wouldnt deem anything hurt or wrong at all based on that oil fill cap alone. the point of the PCV system is to remove that water vapor, if part of the system isnt working properly, your engine never sees high enough temps etc you will get enough condensation to see it mix at the cap.
How...
since you have experience with pushrod motors, most likely in a fox i'll give you a perfect example.
if the fox body has stock size 225/50/16 and the s197 has stock 235/50/18.
the s197 with 4.30 gear would be identical to running a 3.90 gear in the fox, RPM wise.
4r70w first gear is 2.84 vs the 3.22 first gear of the 5r55, so the 4.30 gear isnt a problem if its trapping at a good RPM keep the gear.
everyone thinks you need high gears (low numerically) with a turbo car. if the car is going through the traps at a good RPM and the turbo is spooling well...
low oil pressure to the phaser, cam timing gets out of whack and valvetrain gets loud, increase RPM and pressure increases to the phaser and the problem goes away. thats my theory anyway.