That's a very nice truck! My vote since you're asking to keep the original engine or do a swap would be to keep the truck stock since it is very very nice but that's just me. You might go with the recommended carb swap or at least check out the vacuum diaphragm for the secondary at least to make sure it holds vacuum since they often go bad causing a lack of power. your other post mentions possible blow by and original exhaust. I would if it were me, check out the compression and possibly the exhaust for restrictions. I know my cat disintegrated and plugged itself up. 77k miles isn't much though so the blow by does seem strange. I wonder if the truck has sat parked for some time and the rings may have just gotten sticky/fouled maybe? I once pulled the head off an 84' dodge 400 (same engine as these trucks, well mostly) that had something like 50k and it had lots of carbon build up in the head and on the pistons like it just got driven many short trips which didn't burn off the carbon. I kinda wonder if maybe an oil flush and some seafoam in the oil and fuel and an hours drive may clean things up? how do the hydraulic lifters sound are they noisy? looks like your truck is a base model like mine. I have never seen one with the cigarette lighter delete still there before! the radio looks like either a dealer add on or an aftermarket unit which may be repairable if you wanted too or there are many factory and non factory options that go right in, hopefully yours has the radio brackets to securely mount the radio, if not they are easy enough to get but you will want them even if you go with an aftermarket deck to keep the radio from hanging on the brittle bezel. hope all of this helps!