A bottom bracket question for Concorde owners:

I recently bought an old rather rough Concorde. Not sure of the year or model, possibly a 93 or 94 Prelude or Astore. Can anyone suggest what the bottom threading might be?

More details:
The frame is Columbus SL. There's no model name on the top tube, suggesting it was made for a racing team. The frame colors are black and silvery green/blue, similar to the Collstrop team bikes, but not quite. It is made very similar to the Concordes which many people say were made by Ciocc, but there's no little Italian flag on the top tube. The bottom bracket lug appears to measure 70 mm across, so I'm guessing its Italian threaded.

The bike is pretty beaten up. It was made into a single speed a while back and most of the original parts are gone. The only parts that appear original are the Campy Chorus head set and the Shimano Dura Ace brake calipers, 7403 I think. It currently has a modern Ultegra crank and bottom bracket, but its too beaten up to read any markings on it. Sorry, no pictures available yet.

Thanks