I am putting together a bike out of various old parts. Using a Campy Super Record rear changer. I have a seven speed freewheel, but wonder whether I should be using a 5 or six speed freewheel to work best with this derailleur. Second question is, what make freewheel would work best. Found a number of old Regina's, but they are quite pricey. See some Suntours for much less. Will it make a difference? Thanks for the input.