This bike came in as a stock 1978 KZ650 that had been sitting in a shed for a good few years. We did a bunch of stuff to get it roadworthy, like new tires, steering bearings, chain, fork service and carb and caliper strips. We also swapped out the handlebars for some MX bars, swapped the front master cylinder for a VFR one and installed braided hoses. The headlights came from the Drag Specialties catalogue and I welded some flat bar onto the lower triple for the mounts.
The rear brake caliper on these bikes is a bit on the big size but the budget really didn't stretch to replacement/custom bracket so we just repositioned it behind the muffler using the stock torque arm which we bent to work with the tab we welded on the bottom of the arm. We replaced the rear master cylinder with something a bit smaller and a fitted braided hose.
The owner brought in a small cafe-racer tail he wanted fitted but it was just to narrow for the subframe. It looked a bit like the older CB900F tails so I found one of those and modded it to fit. The subframe was cut down and an undertray and battery box made up. The seat base was made from 1/4" plastic board (the sort of stuff you use for a cutting board in the kitchen) with some of the original seat foam and covered with leather from a skirt I found at Goodwill.
We delugged the subframe and mounted the rear master cylinder out of the way to give a clean/minimal look to the rear.
We did have a charging issue when the build was finished. Turns out older bikes don't have enough charge rate to support two 60/55w bulbs. A change to 35/35w bulbs sorted that.