I have an early to mid 80s Italian built Benotto frame that I'm building up. In shopping for a headset, I've noticed something I've never seen...The threads on the fork are not keyed for the headset washer, nor is there a flat filed back for a French thread headset. What gives? Anyone know what thread/size headset I am to use? I'm looking to outfit it with a period Campagnolo SR headset.