Whats and ideal size to shave off???
You're not gonna like this... You need to pull the head, learn to take some measurements, plug them into a compression calculator, and find out exactly where you are now. Otherwise, if you just try a "ballpark" estimate, you either A) waste time and money not getting the full benefit of your hard work, or B) go too far and start getting detonation, which could get VERY expensive (requiring higher octane gas or an engine rebuild).
I know taking measurements and doing calculations sounds daunting, but this is REAL hot-rodding. You have to know exactly what you're starting with. Bolting parts together relatively is easy. Most of us started out where you are. The hardest part is forcing yourself to learn the fundamentals. It's not nearly as much fun as buying shiny new parts, but like I said, you'll actually get better results.
and since I have that off should I switch out the pistons or would it even matter if I'm not boring it out??
You can't change the pistons without a complete rebuild. (I'm sure some might argue that it's technically possible, but let's just say that, if you have everything apart, you might as well do a rebuild.) If you ARE willing and able to rebuild your engine, it makes increasing compression a lot easier (you can have your machine shop do a lot of the legwork and calculations for you), but if your goal is just "more power", there are cheaper ways to go about it (a V8 swap).
Also, in and of itself, boring an engine isn't
really about making more power. It's mainly done to true the bores. Yes, it does increase displacement some, but the increase in power isn't all that significant compared to everything else.