408 stroker fuel requirement?

Aluminum heads would help. What do your plugs look like, is it lean? My initial is 20, total 34, and I have run 10% ethanol gas, but it started differently and I did richen it up. I went back to BP premium. My compression is somewhere between 10 and 10 1/2. I will admit, I am not an ignition guy, timing coming in to fast?