The original stovebolt rocker is close to 1.5:1. The 1.7 allows for more valve lift without radically modifying the cam lobe. It might be necessary to flycut the piston crown a little, but the piston I'm using has a dish top, so the cut into the piston crown will be minimal. The compression ratio with the stroker crankshaft will be around 9.5:1. About the only thing original about the engine will be the block and head castings and the timing gears. A "216" becomes a 258, A "235" goes up to 270, and a "261" gets 300 cubic inches. Externally the engines look completely original- - - -single carb and exhaust, even!
Jerry
