Swingarm spacing?

[ChristoT]

Don't be too worried about the slightly narrower tyre, the reduction in contact patch won't be very significant. After all, the front copes with braking forces that are just as great as the rear gets from the engine.
There may even be a slight handling benefit: the contact patches of front and rear are out of line with each other when banked over… the more similar in width the tyres are, the less misalignment there will be.
Good luck with the project, I hope you can get things to fit.

First I need a bike to fit stuff to!  :rolleyes

This is an idea I've had kicking about for about a year. I've been working on details in my mind, I hope to get to build it!