Hey man,
It looks like the guy above might have the easiest solution for you if you want a bolt-on part.
If not, another way to go is to make a simple adapter plate. I've seen a lot of guys do this. You just get a thick piece of steel, drill holes to match your new V1902 engine, and then drill another set of holes that line up with your machine's original mounts. A local welding or machine shop could probably make one for you pretty cheap if you don't have the tools.
Good luck with the project, hope you get it sorted out!