Compression @ 80s in all cylinders sounds strange. Did they remove all the spark plugs before running the compression test and have the throttle pushed open (WOT) ? The air tight seal on the intake manifold (and carburetor/throttle body mounting to the manifold) is so vital for smooth performance on the Stovebolt. You have 2 carburetors, so twice as many odds of something not right with the pressure (and vacuum) and possibly the fuel or both. Granted I'm a newbie to this, but I'd start with very close examination of the carburetors, hate to say it, but even removing them, checking the float bowls, checking the gaskets on the throttle/intake manifold plate, gaskets on the manifold to block, etc...
