I have a big block converted maximum st. You cannot convert it to 4wd. It is rather simple to do a big block conversion. I used ofna 1/8 motor mounts, and you have to drill out the chassis for the new mounts. Next you will need to turn your carb slightly so you can make throttle linkage for it. All I had to do was make a bend in the rod, and readjust for my brakes. The exhaust was a little harder to tackle, I had to flip the header around and make a pipe mount that came off the rear shock tower. I used an old monster pirate gas tank and trimmed the top side mounts off, and use the bottom mounting screws. I had to drill new holes for these also. If you go Big block you do not want the 2 speed due to durability issues. Get the metal spur gear upgrade, tighten your slipper, and call it good. IF you have problems with the rear axle hexes slipping or stripping, I used thunder tiger rear axles that use drive pins much better! Sorry for bumping an old thread but thought I would give some insight.