I just recently bought my 79 J20. The owner before me used it as his welding rig and had done alot of work to it including putting in a Buick 350 V8. It started up nicely at the previous owners house. Idled very smoothly, drove it home and a couple times at when stopped it would almost stall out until I would tap the gas while my other foot was on the brake. Once I got home I started it again and it stalled out after running for a few second. After that it wouldn't turn over unless it sat for a few hours. I also notice gas dripping from the carb. After sitting for a few hours I would try and start it again only for it to stall out after a few seconds. If I held my foot on the accelerator it wouldn't stall out until I let off the gas, but black smoke would come out of the exhaust making me think too much gas was getting through. I thought, maybe a sunk float in the carb? After a week I went to start it again to show my friend the problem and it stalled out pretty quick but upon restarting it I held my foot on the gas for a second or two then let it off thinking it would stall out as it had before, but it continued to idle smoothly until I shut it off. Also no gas was leaking from the carb and no black smoke was coming out of the exhaust. Thoughts?