Marc. I don't know how helpful this will be, but I'm playing around with some late 70 early 80 Honda front end stuff.
If the steering stem is 26 mm on the journals, and the steering head is a nominal 47 mm bore then the bearing being used is likely based on the 32005X standard series tapered roller that all the majors supply. These have a 25 mm bore standard and Honda supplies a special with 26 mm bore. I had some modified by a mate with hard steel turning tips
If you have access to a lathe and ceramic tipped tooling it is easy to bore the bearing bores out. For bikes with odd ball gearbox bearing sizes ,often the OD can be turned down.
After I did mine I found that All Balls has a Honda kit with the bearings and lip seals for about the same dosh as I paid for the bearings and turning.
