If you can't afford a 455, what should you build?  

what budget do you run?  

The cost to build any Pontiac engine is pretty much the same, so if budget is an issue, build what you have.  Everyone says build the 455 because it is "free" cubic inches, and there is no replacement for displacement.  Don't build a 301 as it has a small, weak crank.  Just watch what heads you get as the late model heads, 6X-8, have huge chambers making for ultra low compression numbers without pistons to compensate for it.  good luck.
Dan  

A big cuin engine cost minumum 30 k to build and a more stock like engine you can build for 3 k so i do think that budget is important.Mats