1988 GMC 3500K Sierra advice

So, let me be the bearer of good news. I owned a R3500 with the 454. Also several 350 trucks in that era. What’s being missed here, with a little mechanical knowledge and a few bucks that truck will be a decent tow vehicle. Intake and carb, strip the injection, headers and true duals with a cross over will yield nice results. Change the cam and heads and that 350 will easily be over 300 hp. But it really depends on condition, ability and desire. My R3500 sucked in stock form. Exhaust manifolds were glowing red at the top of 5% grades and it got 3 to 4 mpg towing 8000. I figured in fuel savings alone I could afford a newer truck.