or quit making excuses about your own novice mechanical inadequacies... by throwin a 2j in it
OP asked for how to make a cost effective 7mgte in the 400-500 hp range.
short answer: fast, cheap, reliable... pick two
long answer: 7m, 2j debate will never end. haters gonna hate, ballers gonna ball, and the village idiot will half ass a 7m rebuild, blow it up, and blame the engine publicly online with all his nut swinger buddies from the other towns. the web is full of useless regurgitated "some times untrue" information.
first step... budget! figure out what exactly you want out of the car. there's plenty of build threads to sample.
step two... are you qualified to do your own work? if not, are you willing to pay a professional shop?
still with me?
now its time to pick your flavor of jap 6cyl... 7m, 2j, or 1j if your not a fan of tq. they all have there die hard fans and nutswingers what ever flavor you decide is your call.
7m record is 1340whp all boost, so lets just let the #'s talk, haters can get bent...
be prepared to sink $5000-$10000 into your supra to make it last with quality parts no matter what engine you go with.