I'm runnung the Mallory unit w/o an advance, you will need to advance the base timing about 10-15 degrees to offset the lack of the vacuum advance.
If you don't, it'll backfire badly, especially when the engine is cold. As long as it's setup correctly there shouldn't be any sacrifice in performance. I would suggest using a 3rli Hyfire spark control with this distributor to get the most out of the coil, you will be able to eliminate the ballast with this addition.
