Re:
There are definitely others better placed to comment than I, but I made a note quite some time ago of a firm called Calda-Morley who can make custom sizes. I haven't bought from them, but perhaps that's a start.
I don't know what the original imperial spindle diameter is, but I had read somewhere (possibly on here) that one solution was to have the spindle re-machined to an exact 22mm dia. which would allow you to fit metric bearings. Mine appears to measure 22mm, and I have some 22x39x9 bearings - but I have yet to try and fit them. It may be worth measuring your spindle diameter to see what you have.