Well boys, there is always that system being put together to put real brakes on the vintage bikes by a company in Cali... It will cost you a lot of benjamins to get it, but quality is not cheap.
Modern rotors and calipers on the stock 750 and 550 forks...
A very lucky ba*L&*(), er Stiff in Cali knows some people and after deciding to have his bike in a bike show they engineered a means to install their high end brake system with a bracket to us a modern racing style caliper that is well respected and the modern floating rotor design that bolts up to the stock hubs.
It won't do you any good for your modified front-ends but if you want to go with Race Tech's emulators and gold valves and springs then you have a pretty decent suspension in the stock forks or in GL1000 forks.
--fwiw
David