About 4 months ago I ran my motor out of oil. Upon disassembly and inspection I found that the number 3 cylinder had some serious scarring as well as other damage. In short, I am starting to rebuild the motor. I have had many people tell me to just go and buy a motor however I am a hobbyist mechanic, and enjoy rebuilding engines/cars. My mechanical knowledge is sound and I am fully confident in my ability to rebuild the motor, however I have a few questions.

I want to sleeve the block out to a 2.1L. Ive talked with a friend at a local machine shop who has performed this type of work before and sourcing the sleeves and pistons and installing them isnt a problem. Heres where the questions begin. Firstly, I am wondering if I can throw in higher compression pistons? I know I cant go to much higher than stock without running higher octane gas, but maybe something like 12:1? My next questions is will such a motor be able to run with the stock ECU in place and only a V-AFC to tune for fuel until I can afford a stand-alone unit?