Honestly, if you aren't going for a proper restoration, then powder coating the frame is your best bet: it is stronger than paint and lasts longer. Plus is looks great.
If that isn't possible, then just about any single-stage paint will work for you as long as it is fuel resistant (all car paints are, so your uncle shouldn't have trouble finding the right paint for you). Single stage paints include a "gloss layer" to them so you don't need to do a pass of clear coat to get the gloss. In other words, you will be able to lay down a good primer and then a single-stage paint on your frame and be done.
If it were me painting, I would put an epoxy primer on the bare metal (excellent sealing qualities to keep the metal rust-free). Then put down your primer and then your single-stage paint.
For the record, Honda used a black paint with what many call "80%" gloss on the CB750 frames.