I have a '58 Fiat 600 sedan, and I also looked into putting an 850 in it. Here's what I was told: You can do it, and lots of people have, but it's not just a "bolt-on" job. You have to cut away some metal from the car body to make room for it, and modify some other stuff, and you also have to use the 850's engine because the original 600 engine spins the opposite direction. I eventually decided to convert mine to an electric motor and nevermind the gas engines. But the bottom line is, yes it's possible and the 850 engine/tranny will add a lot of "zoom-zoom" to your classic car.

Answer by dobielustra on Apr 27, 2008