I recently got an 84 coupe deville with a 4100. Im trying to decide if I want to drop in a 350 or rebuild the 4.1. I have a mechanic that told me he would rebuild it and replace the sleeve and everything. I asked him about the over heating issues and he said he can build it and I'd never have to worry about it over heating and it would run like a sewing machine. Any thought? I like the fact it would still be all original, it's just what about the power!