I use a factory distributor with 9 degree plates in both my street driven 440's. I use a factory light spring ( I've juggled around some different ones) and the factory heavy (large loop) springs; with vacuum advance distributors. there are different heavy springs like there are different light springs. the only heavy springs that will work with high initial timing are the short ones and they don't seem to be as common (this is specific to using the vacuum advance). there were some factory solid plates that eliminate the vacuum advance which would give a nice full centrifugal distributor. this works well in low vacuum engines and can actually be set up to idle at 30+ degrees at 1000rpm. I have a couple of the FBO limiter plates and the ones I have are not accurate and I don't use them; even though I have figured them out.