I asked this question to Jerry MacNeish about this and he said they did make smooth body distributors and distributors with turn marks on them. The distributor came from Heartbeat City and I've always known them for selling authentic parts.
Did Jerry define who "they" were?
While I did not find any restamped distributors on the Heartbeat website here is a link to restamped 837 alternators that he does sell as restamped units; http://www.heartbeatcitycamaro.com/store/product/21545/Camaro-Alternator-1100837-dated-9C20-69
Thus your opinion of Heartbeat is not correct.