Mike, I just went through this with a truck I got six months ago. It had been sitting for 17 years and had over a hundred thousand miles on it. I could smell the gas as soon as the truck arrived on the flat bed. I removed the tank and had it dipped at a stripping place. I also replaced the fuel line from the tank to the carb. Fuel pump had to go, too. I did what Hotrod Lincoln mentioned above and disassembled the carb, soaked the parts, and rebuilt it. I also had a very thick layer of gummy residue in the intake manifold, so i removed that and soaked it. When I started the engine, I didn't have any problems with fuel flow or dirty gas. I DID have problems with all sorts of other things, though, but since your truck has only 17,000 on it, I doubt you will have the same problems.
I would check the tube behind the pushrod cover, which carries oil up to the valves and rockers, and make sure it is clear. Mine was blocked with crud and little or no oil was getting up to the top of the engine. I removed the tube and found the blockage at the rear port, where it connects to the block.
My engine smoked like a cheap cigar and only got worse. It's coming out in two weeks and will be replaced by a new one. But it did have a lot of miles on it and looked like it was used pretty hard.
