Using idle manifold vacuum is a band aid, but does tell you that the engine likes/wants more initial timing. The biggest problem with using manifold vac to help the idle timing is that it drops off then with throttle.

There are numerous videos on going inside our distributors. All that needs done (usually) is for the slots to be shortened and much lighter springs to be installed. Not really hard at all and can be done with a Phillips screw driver, needle nose pliers and some JB Weld.

Of course, on some low compression engines, you may be able to just lock the advance out and set the timing at it's best total advance. As long as it doesn't hit the starter or ping, it's all good.