Sears Ropers originally came with a 5/8" to 1/2" axle bushing reducer like Dave posted, HOWEVER, they extended FULL LENGTH from the outside of each wheel bearing, for BOTH the front and rear wheels. If you can find one of those, that is one (and easy) way to go. The one Dave posted is only 3/4" long- what would prevent it from "wandering" (inward) off of the bearing? If you cannot locate a full length bushing reducer, you still have some viable options (We have done these on our bikes):
1.Replace your existing 5/8" wheel bearings with 1/2" wheel bearings
USA Bearings and Belts Part # PFR-2214-2RS 1/2" ($ 4.00 each)
2. Drill out your existing 1/2" fork and frame axle mounting holes to 5/8"
It is easy to do and no need to have a machine shop do it. Just purchase a "Step Drill" (Google it). We bought ours at HF for less that $ 8.00, which included 3 different sizes. They are self-centering by design so no worries about holes being out if alignment.
Sidebar: You mentioned that you are going with Azusa wheels. Just a head's up: Watch your wheel/tire WIDTH on the front fork , ESPECIALLY if it is "springer" fork, as the clearance is pretty close.
Good luck with that Roper!:thumbsup:
Michael