360 Mild Build Questions

IMO;
I think you ought to have the bores checked with a dial-bore guage. You can't see taper nor out of round, but your rings will ; and if the rings get to sliding around in the grooves,the engine will soon begin to lose cylinder pressure, which, at 8/1 Scr and with a longer-that-stock intake duration, is gonna make for a lazy bottom end.
BTW
A one thousanth change in bore size equates to over three thousandths change in ring gap. If you set your gaps tight at the top, they will be even tighter at the bottom.