340 to 360 production transition

The bores are 4.04 - 340, 4.00 - 360.
I have had 340’s go south at a .030 over bore. Some have gone to 4.1. I have seen 360’s take a .070 over bore. I have read in the rags as well as from Gary P, Ploy Guru, the early Poly 318 going to a 4.00. Maybe more, I’m not sure.
Sonic check first! Then you know.

Stroker kits are at the ready on shelves. Ether will be fine to stroke. IF you want to not pick and split hairs, the 340 inch is better due to the larger bore and should take the largest piston and smaller crank journals for reduced bearing speed. (Yawn...)