I have been in the business for quite a while, I can say I doubt a tall & long engine like the 2JZ or RB would clear the hood. It has quite a rake to it. But then it wouldn't stop me from shoving an LSX in there! LOL
The oil pan isn't the problem. If you were to dry sump one of your choices, and really try to drop the engine low, I think you would then run into pinion angle, ground clearance issues.. etc & it still probably wont clear.
As for keeping it Subaru. I think an STi or even the WRX drivetrain would be a far easier swap (due to Subaru lego-ness) and create little to no physical obstructions.
As soon as I get tired of the weak ass 3.3 its gone in favor of an EJ25/6MT.
Good luck either way, it should be fun. I am all about the engine swaps.... Started way back in the day with a bet that I could swap a SBC into a 88 Starion ESi-R to be rid of that POS truck motor G54Bt. 6mo later I was driving it. Of course the StarQuest guys hated me for it. Not that I cared.
