Its an A1 block, but still the web between the main bearing bore and the pan rail is quite thin.
I'll have to take a close look at the lifter bores. Dave, thanks for the referral, I'll give him a call.

Aftermarket heads can flow 360+ on the intake...

I bought this billit crankshaft off ebay, it turns out that the seller was John Calvert and he said the crank checked out good. Today I dropped it off to be magged anyway, just to be safe before I start the build.