Heh, finally something I can talk about. This is my first actual post on here, even though I've been lurking for a long time.
The 1JZ is just as stout as the 2JZ, just simply a half liter smaller. It revs very smoothly, has a ton of potential, and is an absolute joy to drive. The stock turbos are worthless past 14 psi, so for your 450 hp you'll be upgrading your turbos, fuel, and intercool i imagine. Personally, I would pursue a 1JZ half clip, as opposed to an engine set, but since this is a custom setup it my not be as desirable. I'm preparing to put a 1JZ into my mkIV supra (NA) to be a little different, not to mention that it is still an awesome motor. Some more points to consider are that the 1J head is reported to flow bettter than the 2J and can also bolt right up to a 2J 3-liter block (known as the 1.5JZ)
By the time you spend all the dough getting a 1J in, you could have a very strong 7M in your car. Not to mention, there are people you can turn to since the 7M has been done before. There is tons of knowledge out there about the 7M, whereas the 1J has really just exploded in tthe past 2-3 years. Depending on how you like your motors, the 7M would probably acccomplish your goals with a smaller budget, although I'm not sure how reliable they would be at 500+ HP. Personally, I like high revs and could care less about torque, so I like the JZ series motors over the 7M.
I know almost nothing about the RB or L series motors, but I'm pretty good with the supra stuff.