I think there fairly universal, since most distributors are spun on a machine to verify the advance curve characteristics, any changes to the springs and weights can be made at that time. Sometimes, final tweaking is necessary by grinding on the weights slightly if the ones in the kit aren't exactly the right amount of weight(too heavy)!
There's no such thing as too much cam....only not enough engine!
Loc: Fallbrook, CA, USA
Every so often I see this subject come up on the bulletin board and can't resist answering because of the great performance improvement (idle thru full throttle) I experienced on my 302 GMC. Fitst, I recommend you get an HEI distributor. They were made for the 250 and 292. Second, read and follow two articles. http:// http://www.boyleworks.com/ta400/psp/distcurve.html and http://members.aol/dvandrews/timing.html. The key is to use strong springs and re-shaping the center plate as the second article indicates. When you search the internet for these two articles you will get many more on the subjest as well.