What are you trying to accomplish? Unless you are going to change more than just the distributor, I don't think that you will gain a whole lot. If it has good vitals (compression and oil pressure) and you just want a dependable driver, I say go with new points, cap, rotor, plugs, etc. It should run great, and will not cost you much.
If you want to go the high performance route, the distributor is just one component. You would also want improved carburation, intake and exhaust manifolds, and possibly at least a mild race cam, to reap a big gain.
It is all based on what you really want.
