Dura Ace 7400 bottom bracket question
 

I have an old Reynolds 531 track frame that has an English threaded BB. The problem is the BB shell width measures 70mm not 68mm. I’m using 7400 DA cranks with the ring on the inside position.

I’ve tried my 7400 BB and even with non-drive side cup in all the way, the spindle still has some side to side play.

I can buy an Italian 7400 BB that has a 70mm spindle and use my English threaded cups and the longer Italian BB spindle.

Before I do, I need to verify a couple of things

1. Are the 70mm spindle and the 68mm spindle the same diameter? Same bearings?
2. Chain line. If the 68mm spindle gives me a 42mm chain line, the 70mm should too since they were both designed for the 7400 cranks?

I’m using a UN72 cartridge BB now and it works but I’d really like to use a loose ball 7400 BB.

Thanks,

Dave