IMO it looks a little silly with such a rake on it but thats also what makes it look cool. If you put a little china girl on there you shouldn't have many if any problems at all.
Good luck on your quest! I will be watching this one for sure!
Slim.
With a HT, I feel that the chain may give a little problem, with stock the mounts. It appears that the engine will have to be mounted higher. With the engine mounted higher then normal, I don't think the chain will be a factor. A engine out of the box with factory mounts needs a 75 degree angle for proper fit. So it looks like the engine will have to be mounted higher with a custom mount/s. Also a custom rear mount so the rear mount is higher for carburetor leveling. But it can be accomplished if you have the ability. Then you might have to build a inframe tank or weld a bar to hang a tank.
That's my $0.025
Need 5.5"-6" minimum with stock mounts. With a 60 degree angle the mounting of the engine will need to be higher. Although by removing the rear mount, the engine can sit lower.
If you decide on this route (a HT engine) I'd make a mount for the rear, bend it as needed (to level engine out) then do the front mount. On a normal frame we just bolt the engine with the rear factory mount, then work on the front, and engines are basically leveled, but I see that you've already have one finished.