I would recommend that you seperate the task into 2 distinct phases:

1. Building/aquiring the engine and transmission
Building a 400HP 302 is doable, but it could be difficult without experience, expensive parts, and probably a supercharger. I've seen lots of folks build 302s that end up making 300 to 350 HP when they expected more. The cheapest way to get to 400 HP is probably a crate motor 347 or 351.
Another option would be to buy a donor car such as a Mustang that would give you the engine, transmission, and all of the other related parts and pieces that will kill your budget and schedule chasing down seperately.


2. Getting the drivetrain to fit and work in the car.
This will take longer than you expect, and there will be a ton of details to deal with. For instance, when pulling the engine out of a 960, be carefull not to let it tilt back too far or the back of the head will smash the brake lines that run along the firewall. I'm almost done with this phase, but I expected to be driving it weeks ago. Having a running engine to start with has made it a lot easier.

Good luck.
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