Gearing up for higher speed will be a waste of time because the engine won't have enough torque to pull the higher gear, particularly with a load on the truck. Either get used to running slow, or buy another, newer truck. One option might be to find a 261 engine and replace the old splash-oiler 235 that it's probably running now. I'd definitely keep the 2-speed rear end and find the tallest tires that will fit the wheels for a little more top end speed.
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!