1) BBC 4 point rear mount are pretty easy to find, seen some on C/L last week
2) Flywheel or flexplate may already be determined on existing stringer mounting holes, I run an auto flexplate on 3 different boats, and if/when I have to replace one, I'll use an SFI approved one. If I rigged a boat from scratch, I'd use a junk aluminum flywheel.
3)Pump should have some resistance, but dont wory too much because replacing the bearing/pump refresh is pretty easy
4) 3 boats, 2 trucks and an xr600... Delo 15w40 (good sh!t)
Just my $0.02
Daniel
Mash on it