you would only be able to put those engines on if they are horizontal shaft which a lot arent. Also dont think about using the leafblower engine because ive never seen a leafblower with more than a 70cc engine which would carry around 8mph so yeah and that would be pretty hard to do if you are not to experienced because there are so many thhings u have to do
i say just buy one from cjtmini he gives you everything u need and it is a fast engine