The under-floor master cylinder used with most 1/2 ton conversions won't have enough volume to work with 3/4 ton components. Make sure the master cylinder can move enough fluid to get all the brakes applied without running out of pedal stroke. Those tiny booster diaphragms are also short on power- - - -they're better than no boost at all, but not by much. I'd choose a firewall mounted booster with a big enough diaphragm to get the job done and a larger-bore master cylinder.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!