you want honesty so i'll be honest --- one of the big reasons why i loved your car was because you used the original engine (and even exhaust/intake manifolds) to make over 500hp.
if you go the 2jz route, i think you'll have a great engine and all, but it just won't be the same. it's like cheering on barry bonds after you found out he used performance enhancing drugs, it's just not the same. plus the list of 600+hp 2jz's is very long, and that can't be said about the 7M, so that's why personally i build up the 7M.... it's more challenging, there are more milestones/records to be broken and it's original to the car.
whatever you decide to do, make sure you have some play money in case soemething blows up again even if you have to put the project on hold for a year or two to save up.