We built a BOSS Block in december Serial #3xx for a 347. The tech line was fumbling for info at that time.
We figured out the following HEAD gaskets work well; FMS-M-6051-S331 (available where FRP are sold, buy 2 sets as these go on BO freq.) we used this in concert with an edelbrock performer RPM AL head.
Head stud kit ARP ; ARP 155-4001 FE Kit, works fine. Block bolt(head bolt) holes are deeper and threaded lower than a regular 5.0L/302 block.
The block plug kit came installed in both blocks we have bought. it also came with a bag of goodies. (pins, plugs)
the block is awesome, hence we are using it for my 331 (final CI
TBD) for my MkIII SPF.
The block is also tapped for a clutch pivot stud, and the sheet metal frogs for holding the roller lifter spiders in place.
Sooooo The price of admission is higher, as a factory fresh 5.0L block is about 600, and the Boss punches in at 1800 but as a nice foundation for a 302 form factor engine.
Thinking out loud, I am wondering if they could come up with a BOSS 351W block to make 427Ws easier and beefier.
Have yours built; with the exception of the roush, crate motors are for camaros...
--Steve