Rebuilding distributor

How do you know the springs are shot?
Are you staying with the emmisions timing at idle?
vac can's can be expensive. New diaphram can be put in - also not cheap. Which type is on that prestolite?
For performance, the Chrysler distributor for the engine is the best advance curve - except for the emmissions deal. That can be adjusted so you can use a pre-CAP initial timing on the order of 10-12* BTC at 600 - 650 rpm.