Hey Motomagz,
You have built another beautiful bike! You should be proud. Sorry I’m coming to this late, but in regards to brakes for these higher powered machines, I can not recommend more highly the use of a small motorcycle front hub. I learned this a long time ago from the guys at BigBoy Cycles. They had a bike at the race track and they were using a Honda C110 front drum brake. I bought one about 5 years ago and have never looked back.
Using my stock spokes with a worksman rim, I laced in the hub as you would a regular bicycle hub. Geometrically the spokes work even though the hub is much larger. I did have to fabricate a lobe to keep the hub plate stationary, but other than that, use a motorcycle brake cable and this brake stops me quickly even when I’m rushing up to a traffic light at 45mph and it suddenly turns yellow. The front brake is so effective that I still use a coaster brake in the back (vintage Morrow Hub).
Looks like you’re already going disc brake, but just thought I would share.
I wish you didn’t live so far away, it would be fun to ride alongside your awesome bike.
Gilbert