So based on what i have said,where would my compression be at,lets just say had the heads milled down to 58cc's?would it be around 9to1,higher/lower? OldManRick you say notches are correct for rebuilds?
What i mean is stock replacement pistons usually have notches like factory pistons, but the replacement pistons are also available in multiple oversizes. If your bore is more than 3.91 then i believe it has been rebuilt at some point with a factory style piston that had a overbore that was enough to clean up the cylinders at that time.
As far as comp. ratio i hope a member with access to a good formula can come close for you, but if your chambers are milled to 58cc's you should have a decent comp. for a driver, but the quench in the cylinder would suffer from the piston being down .050.
The best case scenerio would be the piston at .000 deck height, level with the deck, and mill the heads to achieve your desired comp. ratio.