help need some info

Building your 302 is easiest, then swapping in a 351, and a 400 will most likely be a PITA. Even a 351 swap is pretty elaborate.

First off welcome to stanget! For us to really be able to help you, we will need to know what you want out of your car and what kind of budget you are working with. Also tell us what the current situation is with your car as far as condition, miles, motor. As far as motors go there is the most support for 302 based motors, the next best would be for the 351w (which can be stroked to well over 400 ci). There are a lot of very helpful existing threads on here that can be found using the search function. I suggest doing a ton of searches and a ton of reading. Good luck on your searches and let us know if there are any other questions you may have!

you could probably make that 400 work but you'll probably be blazing your own trail on that one. 302 and 351s are common and have the support of the aftermarket. I'd agree with Shaun though. we need to know more about your car now and your hopes for the future before really being able to help you out.