I would not use a automotive engine. Bolt on parts and even your engine mounts may not fit. The heads on the larger 4G engines are different than automotive. I have heard many horror stories of people trying to get by cheap using a automotive engine and actually spending more in the long run. If you do a search for Mitsubishi forklift engines you will find several reputable rebuilder. These engines are very popular in the forklift industry so there are also a lot of cores out there if you plan on rebuilding one. A couple of companies that you might want to check with are Char-Nor, Grindstaff or Pioneer.