With pistons machined to where they all have Zero deck, you still have too high compression for your CAM and FUEL. Your cam is very mild, and it means it does not "lose" compression through open valves. BIG cams keep the valves open longer, and some compression pressure is lost, so to compensate for the loss, the compression RATIO needs to be higher, just to maintain the same actual cylinder pressure.
So your engine is not junk. It's just a combination of parts that can't work together. You basically have two choices (Extremely simplified): Lower the compression ratio to match the cam, or change the cam to a much bigger one to match the compression ratio.
Those two pieces of your puzzle need to match.
Because you already have the cam ($$$) and modifying OTHER parts of the engine to support the much bigger other cam is expensive, and you are not building a race engine, it means you really only have one option: reduce the compression ratio.
Now you need to figure out HOW, and it may need a combination of several methods:
1. piston dish needs to be bigger. With the MILD engine you are planning to build, you could make the existing piston dishes larger. (new pistons = $$$)
2. remove material from the combustion chamber to make the volume larger. This is beneficial too if done right, improving flow around the "tight side" of the valves, also known as "unshrouding".
3. Use a thicker head gasket. Your "deck height" with a normal gasket is about .040" (1mm) which is fine for a performance engine, a little on the tight side. You could use a gasket that is maybe .050" (1.3mm) thick. This you would need to have made for you, using a stock gasket as a template. You could have it made of copper, it would also be reusable. Much cheaper than new pistons or cam or changing your whole engine design.
4. maybe not a real option, but changing the cam timing also affects cylinder pressure. You would need an offset cam or crank gear key.
5. Change the cam to something similar but with bigger LSA (lobe Separation Angle) to reduce cylinder pressure. You can ask a cam manufacturer to make a mild cam with a bigger than normal LSA for you. Unfortunately this means buying a new cam.
I just ran out of time, I have to run to work. Others please correct me where needed and continue with your ideas
