New in here need some advice SB 360 Cam selection

Hey good to hear from you! Glad the exhaust worked out; it wil lmake a very noticeable difference all through the RPM range.

Those indeed look like stock early 360 pistons.... dished tops with around 8 to 9 cc's of dish volume. The small notches are probably the orientation notches on the pistons.... they should be towards the front of the engine. The arcs you have drawn that look like eyebrows are probably light reflections from the cylinder walls.... they are too small for piston eyebrows. So this is a low compression engine, even with the heads milled 1 mm. Maybe 8.3 or 8.4:1.

Thanks for taking the compression readings. The compression readings are high for that engine, even with the heads milled that much. So I suspect this is more like a stock 2 bbl 360 cam. Or it is a 340 cam and is installed with quite few degrees of cam advance. Or the compression gauge is in error.