You'd have to calc it out based on your squared deck height, it's not likely to be zero deck but should be as good or better than most OEM builds

RB is nominally 10.72"
a B is nominally 9.98"

RB stoke is 3.75"
B stroke is 3.375"

RB rod is 6.76"
B rod is 6.36"

Assume most Standard OEM pistons put the slug around .100-.110 below deck, Six packs, 68-71 340's and 68-69 383's generally were a little better than that.

I suppose if you had a 426 block you could build a 484" motor using a low compression 383 piston.