What does your advance curve look like? I don't think you need vacuum advance if your distributor is setup right... I have a stock-short-blocked Ford 300-6 (about 8:1 comp) with no vacuum advance, and it runs great, except for the flat cam....
Anyway, what are your initial and total advance numbers, and at what rpm? Do you have a timing light? If you don't, that's the first step.