Worked on getting the engine to smooth out and was finally successful. Along the way, a new Pertronics electronic ignition went in along with a fresh cap and rotor. Fresh plugs too for good measure. But none of those things did the trick, of course. When I was just about ready to go for a timing chain set, I thought that first I should try putting the original carb back on. The seller said it had worked but the accelerator pump wasn't right so put this Edelbrock/Carter on instead. I figured at least if the symptoms changed, I'd know I was on the right track. So I pulled the E/C carb off and was starting to transfer the fittings over to the original when I realized there was a chunk missing from the gasket. Thinking I might have found something, I went and looked at the manifold. There was a chunk missing there too... not on the manifold itself, as I thought at first, but on this phenolic spacer, right between the exhaust crossover and the right primary venturi! OMG! The exhaust is getting sucked in there big time! A quick trip to Coopers provided three gaskets and two shims to approximate the same thickness as the broken phenolic spacer and PRESTO, she purrs like a kitten, has excellent vacuum and starts right up! Problem solved. I phoned the seller to let him know and he was genuinely pleased. Man am I relieved!