Whoa Pard! Lets slow down for a moment everyone! Bent valves? As stated, the engine runs. Good. Fuel system should be first on the list. Get the tank and lines and filter cleaned up. Then if no improvement, then get a carb kit for the carb. There is no GMC 345 by the way. It's either a 305 or a 351. Then once the fuel is clean, then twist in some new plugs, but not before you have cleaned up the fuel system. Then points and condenser, etc. After that, how's it running. Still crappy, THEN it's time to investigate further. A new clutch may not be a bad thing. Slow and steady as she goes.:) It sounds like the mechanic is intimidated. You need a real old timer who really wants to get in there and mess something up....I mean fix it!
