Sounds like you do not have enough vacuum. There can be several reasons for this including a lack of flatness in the bottom of the carb or in either side of the spacer. First measure your vacuum at idle.
Again. Funny you say that. Just got done putting the vacuum guadge on it. At idle it's reading 10. When I give it gas it jumps to 15. If I'm not mistaken it should read zero until I give her gas. Timing was set with the vacuum disconnected and plugged. What next?????
Vacuum gauge is connected to manifold vacuum. If you have power brakes there should be a tree behind the carburetor coming straight from the intake manifold. Have you taken a compression check? That's the first thing to do in a tune up. Like 351 said, the vacuum is very low, it needs to be 15 or more at idle with the stock cam.
Number 8 cylender is reading 65 psi. I don't have the skills to do a rebuild and the time with a 3yr old. So I'll save my pennies and get a crate motor or find a low milage donor. I can easily do an engine swap!!!!! Two days work.