No need to machine the cranks if they are the original ones. Pace machined all their bullseye spindles down to 22mm from 7/8"(22.2MM).
Just get either of these bearings. Common motorcycle wheel bearing size.
http://www.ebay.co.uk/sch/i.html?_from= ... g&_sacat=0
-2Z looks more authentic but the sealings not too clever. I prefer to run -2RS with rubber seals for longevity. I remove the inner seal before fitting so the seals don't press into the races when you inject more grease into the bb.
Looking forward to seeing the progress on this, good luck!