There is nothing fundamentally incorrect about using a Shimano freewheel on an SR equipped bike from 1984. At that time, a lot of people used high quality Japaese freewheels with their otherwise all-Italian bikes. The more popular choice was the Suntour New Winner which is an excellent freewheel. The regular 6 and the Ultra-7 both fit into 126.5 frames and were both common. As I recall, by 1984 Shimano had just introduced the new Dura-Ace screw-on freewheel (MF-7400?) and this too was an excellent unit. Either is far more reliable than the CX.
The CX would be the "correct" freewheel in the sense that it would be the likely OE on a complete "factory" bike. Regina was the "Campy" brand. Sometime shortly before 1984 Campy, Regina, Cinelli, Columbus... a bunch of Italian makers, were marketed in the US as the Ultima group. An "Ultima" bike would be equipped with a Regina FW.
As for Campy freewheel, they were simply "too much." Too expensive, too light to last... for special events only and even then quite the indulgence. Very cool though.
Tom Dalton
Bethlehem, PA
---------------------------------
Do you Yahoo!?
Yahoo! Tax Center - File online, calculators, forms, and more