As for the sleeve, anything is possible. Just have to provide enough green to the right person in order to acheve the results you want. You can get 850 horse reliably with 87 87.5 88 and 89 bore pistons. All are good for the block without sleeving. Pair that with the correct breathers and garret 2860 or 2863 turbos and your off to the races. But again. 30+k in parts and engine alone for that build. Plus then you need to prep the chassis for the extra power. It is a lot of work.