Remind me again what forks you're running?
This is none of my business, and you're doing a great project overall here, but I implore you to think seriously about changing up to an RSU fork with proper cartridge damping instead of those things with the anti-dive plumbing. The irony is that the original forks from the 70's look less dated than the not-thought-through anti-dive stuff.
You could sell off the forks you have now for maybe $100 and pick up some nice F2 forks for $200. For an additional $100 outlay, you could transform the character of the bike for the better, and make a non-trivial improvement to the looks. If you're going to go to all the work of fabbing up a custom axle, bushings, spacers etc. to fit the front wheel, why not fit it to something that's actually good instead of something you just happened to have lying around the garage?
Or, for a super-classy touch, if you decided you could live with a single brake, you could go with these forks - which to me seem like the perfect item for a vintage/classy Honducati.
Marzocchi RSU's