Ok, I'm shopping around for a new motor, like a 400 or 406, ... either way, it'll be an old style engine (PRE-87) and I haven't purchased an intake yet BUT, how hard would it be to use a TBI (because I still want to have it compatible with the computer.. with a custom chip of-course) would I just be able to buy an old style intake (for a carb) and get the carb-to-TBI adaptor plate, what would happen to EGR, would I not need it for an old style block and heads ??? any suggestions, advice would be great... thanks

 

The intake does not care what the block bore is. All SBC blocks are compatible with all emissions devices.

The choice is more determined by what heads you use, and what intake. There are lots of heads that are suitable for 400s that support EGR; and there are lots of carb intakes with the exhaust crossover are suitable for sticking a restrictive TBI on them with an adapter. You don't even have to have 87-up heads to do that, as long as the heads have exhaust crossover passages like all stock ones have had since 1955, and you run an intake that has it too.