Back in 1973 and 1974, Campagnolo gruppos even through mail order were so expensive that it was often cheaper to buy an entire bike and THROW AWAY THE FRAME in order to get the campy build kit. The OEM discounts must have been very steep as the savings were passed on to the consumer. The most common "Parts-Donor Bikes" in this era were (in order of increasing bike cost) :
1. Windsor Professional 2. Raleigh International
Carlton Cycles pumped out 10,000+ reynolds 531 bikes in 1974, and I think that several thousand of the 'International' and 'Professional' models were part of that production. I don't know the exact numbers, but I doubt that MASI USA produced more than a few hundred frames in 1974.
With many of these donor bikes languishing in garages across the USA, I don't think there will be any shortage of parts for MASI bikes with PAT 73 (typically found on '74 bikes) on the cranks, derailleurs, and hubset locknuts.
- Don Gillies
San Diego, CA, USA