Yes, I think 113mm Campag is the alternate way to go.
Anyone else have any thoughts?
Campag & Mavic use the same BB/crank taper. From memory the standard double Mavic 631 BB is 114mm. I still have one of these BB's (now gathering dust) and used it with a mid 90's Campag chainset (designed for a 111mm BB) without problems. Another friend has one of these BB's mated to a '93 Chorus chainset and in nearly 20 years he has had no cause to touch the BB! The chainline on the Mavic can be slightly adjusted as there are lockrings on both the drive and non-drive sides. As for chamfering the BB to accept the bracket, again this is a very slight chamfering and causes no damage to the threads. I would use the Mavic BB with the Mavic chainset as this unit is miles better quality than any of the sealed Campag BB's. If not then as you say , 113 Campag is on the money length wise. If you ever wanted your BB chamfering I believe Paul Hewitt Cycles still have the chamfering tool.