flackmaster wrote:
I have a friend with a 36*120 with a dual master cylinder and a small vacuum booster. However....

The answer is NO. Nobody makes a kit to do this. Every one I have seen (and I've seen at least a half dozen) has been slightly different, the result of personal engineering skills. Think about the liability to sell a kit to retrofit brakes on an automobile. Not a territory I would want to get into.

Can it be done, definitely.

Should it be done? What's wrong with the brakes the way they are? Up into the 60's Ford and Chrysler were still using single master cylinders...My 120's are perfectly safe and drivable with factory setups...