Dean-
One possibility could be that 2mm was removed from the non drive side only. That might explain a 70mm set up providing the correct chainline. I am assuming you are using Pista cranks with a 151 bolt circle.
For a time, 70mm pista spindles were harder to locate than Italian cups, so maybe.
In 1975 I had to special order mine, got it as a spindle and used old Italian cups from the bike shop stock. Italian Pista bottom brackets were not on hand at the distributors.
John Jorgensen
Torrance Ca USA