The project came with a front master cylinder and caliper from a mini-moto! Just one of the many bodges.....
Swapped the fork legs so the caliper sits behind the forks, had the disc drilled, fitted a braided hose and modern pads. With the reduction in the bike's weight the braking feels ok, but I have an AP lockheed set up I could fit, if I think it needs improving
There seems no issues with the caliper behind the fork (I use a digital speedo, so the speedo drive is not an issue). I did the same on my TZ Yamaha and it's been working great for a many miles
For carburation I upped the pilots by 1 and the mains by 3 and it pulls really smoothly throughout the rev range. There is a slight popping on the overun, so a little bit of tweaking is needed