A stock 302 distributor has 14 degrees(28 crankshaft} of distributor mechanical advance at around 3200 engine rpm.With the initial 5 degrees,a total of around 32-34 degrees.A 235 Chevy distributor will drop right in, or the vacuum advance unit from a 235 will work on the stock 302 distributor.I believe a 235 dist.has a little more than 14 degrees of mechanical advance,probably not an issue for casual driving of a stock engine so long as it doesn't ping.
Be carefull on those HEI distributors used in older GM 6's with a hold down clamp like a V-8.Since the stock set up uses a kind of floating clamping,the original machining of the distributor pad wasn't critical.When clamping down the HEI,do check to make sure the dist tang doesn't push down on the oil pump drive more than necessary which might cause a siezure of the oil pump.It has happened before from what I hear.
Richard,that HEI module using points is interesting.My modified GMC 302 has a multi spark CD ignition box trigged by the stock points,and yes the points last a long time.But electronic switching of the coil is most likely more accurate especially since many old distributors are worn.
