I favor keeping things original to maintain the
historic value/preserve history.
I would not change brakes.
I would change the rear gears if you can find
lower ratio gears that will fit.
I have read too many threads were people went the
two carb, dual exhaust and wound up with problems.
If one must give in to changing only do what can be done
by bolting on without cutting, welding, drilling, so the
truck can be brought back to original. Jeffrey