Check my work-Chime in please

bore of 3.665? My brain hurts. I thought the stock bore was 3.630? A 3.635 bore would make a 273 actually a 274.8 Hmmm, Ima thinking a 30 over hole should be 3.660?
Oh I get it it's a .035 overbore. But why? What am I missing?

I musta done something wrong cuz I get a Scr of 9.64, and a Dcr of 8.47.

I get a swept of 572.22cc, and a total chamber of 66.237cc; which is head of 62.5, gasket of 6.176, and deck clearance of 2.439 pop-up