Brainstormin' 440 vs 5.9 ...

You want the BB, just do it. Said it in the thread. Always planned on a BB for it.

Port the iron heads, 509 type 108 lsa cam in at 100-102, headers, RPM/street dom intake, 1-2" super sucker and a true 850-950 carb.
Heads will make it go... they (oem) are the choke point.

Good 3000-3500 converter (likely most important piece)

Go have some fun with it.