Putting money into "hot-rodding" a V-6 in a full-size truck is a sure path to disappointment and insanity.
Fix "Safety" items FIRST: Brakes, steering, suspension. If this is a 2WD, I bet the front wheel bearings have never been repacked. Keep in mind that the rear brakes were garbage when new, and they're not getting better with age. They're practically guaranteed to be WAY out of adjustment. If the control arm bushings are original, they're guaranteed to be at least partially-failed or worse. Ball joints and tires and steering linkage are more important than rocker arms. The circuit-boards for the rear taillights/turnsignals/backup lights are a known, epidemic problem. Check voltage at the headlight connector with the engine RUNNING, I bet you're at 11-something volts when you want to be at 12.8--13.2 for each light. Not lower, not higher. And "zero" volts on the ground wire for each light.
AFTER the brakes, steering, suspension, and general safety items have been verified, get the engine to run
right--no weak cylinders, no faulty fuel system, no deferred maintenance, no "codes", no plugged catalyst.
Save your money for a real engine, and the heavier-duty transmission you'll need when you blow the original.
Loud's overrated and tinnitus sucks.
Not just "yes". HELL, YES!
The LAST thing most teen-agers need is to have their vehicle noisy enough to attract the Police. You'll have MORE fun with less risk if the vehicle is quiet. And a 90-degree V-6 with loud exhaust sounds terrible anyway.