[Excaliber]

Vacuum advance comes into ONLY at light throttle or idle conditions, it will have virtually no impact on 'power'. Interesting that it made the engine run worse when hooked up (btw, I recommend direct intake manifold vacumm for that advance). Making the idle worse indicates you have plenty of "base" advance, so thats good. As long as you get decent MECHANICAL advance at around 2500 rpm or so thats enough to give you good power. I would NOT worry about 'tuning' the springs and 'dialing in' the distributor yet. I might even leave the vacuum advance disconnected for now.

IF indeed the motor DOES lack power (a very relative term) you have a problem bigger than 'tuning'. Valve lash to tight? Like MadDog suggested, 360 weren't great 'power' motors so maybe your expecting to much?

A friend of mine has a 352 in his '64 Galaxie and complains of a 'lack of power', compared to his brothers 390 in a '64 Galaxie. He says he's tried everything, 4:11 rear gear, bigger carb, timing\tuning, etc. Well, it's a 352, it aint gonna make power like a 390 no matter what!