Torn between 360/408 and 440
I put a 440 in a 74. I did the DC k member conversion detailed by Jim Lusk on the old bigblockdart forum.
I built my own power steering pump bracket and modified a blower motor to fit.
It was great for smoke shows.
Previous to that I ran a 360 that was a exact copy of the little red Express engine. The car was fun but not super impressive.
I've never tried a 408. Never been in the budget.
The only way I'll ever do another RB in an a body is if the Schumacher headers are available again.
The header clearance is the real downfall of an RB in an a body. Everything else is just nuts and bolts.
I would be more inclined to do a 400 over either a 408 or 440. Futs better than the 440 but heads flow better than factory LA or magnum heads.
Easier to fit exhaust on the b engine also.
But I do everything as cheap and budget friendly as possible so aftermarket heads and such are rarely on my radar.