Poor idle and off-idle performance after distributor swap

As always with an edlebrock, especially after it’s been rebuilt, check and set the float levels so they are dead nuts. Make sure you have zero vacuum leaks of any kind. As you’ve said, disconnect the vcan and disregard it for initial tuning. Bring it in later and use ported vacuum. The statement “timing was jumping all over the place” worries me. It should be stone cold steady regardless of carb settings. Sounds to me like you have multiple issues that need to be systematically worked through.