cylinder bore size?
 

what can a bowtie bbc be safely bored to without filling it?

All SB Bow Tie blocks are not the same from the beginning although they all use the same casting number. You really need to know which Bow Tie block you have or get it sonic tested.

BB Chevy Bow Tie blocks they made three basic versions. The gen IV will bore to 4.560 and the Gen V and Gen VI will bore to 4.600

Ed