7M-GE to 1JZ-GTE, questions

[essial]

OK guys, you may remember me way back when I first got my supra. Replaced radiator, distributor, etc. Now it has bad rings on top of the never solved odd idle issue. Thankfully I found a local mechanic that works on cars like mine and is a friend of a friend so his prices are very good.

The plan is to pull out my very much worn out 7M-GE with a quarter million miles on it, and put in a 1JZ-GTE with 50k on the odometer. Of course this also includes the transmission, inter-cooler, computers, etc. I've also requested that if the stock turbo pressure release doesn't have that nice PSHH to it to put on aftermarket blowoff valves as well -- pointless I know but I love the sound.

I've been told that it can be set up to get about 300hp out of the box as is. I was wondering what changes would I be looking at to push it up to the 400-450 range in the future? After the swap I'm going to work on finishing the interior and finally the exterior, but want to go ahead and start saving up for the first set of engine upgrades in a few years.

Really really excited about the 1JZ, I'm so tired of looking at "The Smokenator" and not being able to drive it for months on end.. a few months and I'll finally have it in good condition.