I would also suggest adding a fuel filter just prior to the carb. either a clear plastic or a screw in type at the inlet. I have done this twice now, one prior to the fuel pump and one prior to the carb. If you have a glass bowl fuel pump, clean that out as well. There may be some floating or shifting junk in your gas tank too, I don't know if your truck has gravity flow out of the tank or a pick up screen and plumbing out the top. If gravity flow, pull the shut off fitting and see what comes out. If plumbed out the top, the filter on the end of the pick up could be clogged too. The fuel deterioration advice is good too.
I am going to sing my usual song here, and tell you that a Carter YF will make you life easier than the Rochester will.
Once you get it running , try some sea foam or top cleaner to clean out your system.
A compression check may tell you some things too probably should start with that, clean up the fuel system, and check the timing, points, distributor vacuum line and advance and clean the plugs.
