vacuum question

At the risk of getting flamed I'm going to say, it depends. It's generally accepted that you would want to use the timed port for your vacuum advance just as the factory did - and that would apply to you too. But, with the right vacuum advance pod and setup, manifold vacuum will work correctly too. Case in point: Don over at FBO sets up his distributors to work with manifold vacuum and I can attest that they work just fine that way.

The general problem with using manifold vacuum with a stock dizzy is that at idle it may actuate the vacuum advance causing erratic idle, 'hunting', and other problems. Save manifold vacuum for your reservoir canister.