While more fragile, I don’t think he will be breaking any with a 5K budget. Even at the best full tilt effort he can muster.
Depends on the year B body. So that is now moot.
Minus the price of the car, your not building a crazy high HP engine. The car he wants to build is not a heads up super speed demon. Just for fun. His dollar cap is hypothetical. As in a limit for forum members to limit there suggestions so he doesn’t have to scroll through “Get a stroker 2G HEMI from Barton!”
Hence the suggestions of later year FMJ & B bodies since there often cheap.
It has been written that there birth was an attempt to enter the Pony car arena by simply shortening the B body. No A body thoughts were put into he design. Only bin parts in use already.