Re: Need help with some direction.
Is it just me, or does it look like that seat tube is tapered, narrower at the bottom, and wider at the top?
If you have a dremel, you can grind off the edges of the mount, right where your arrow is, so that the mount will fit properly around the tube. Or, if the tube is tapered like it looks, you can remove the pedal chain guard, which will allow you to drop the engine a little lower, maybe low enough to get the mount around the narrower part of the tube.
But you do need to do *something* to get that rear mount snug up against the seat tube.
Washers ... I think 8mm washers should do you fine. Get a bunch of 8mm and a bunch of 6mm. You didn't mention whether you got a front drill mount plate in that kit - if you did, put that in there, too, close to the engine. It'll give the washers a flat surface to sit against.