UK here also,
Some blank vin plates are remade mostly by one make specialists for restorers . You could contact David Silver if he hasn’t got any he may put you on to someone who has. Then use stamps and put your numbers on . It must then be permanently affixed to the frame.
As far as the legal requirements go the relevant number as shown on the V5c should be displayed on the frame on a metal fixed plate. I made a custom chop using a hardtail frame and most of a Triumph. The original T140 frame was baldy twisted following a collision with something hard. I stamped a aluminium plate with the Triumph frame number and riveted it onto the chops headstock. ( The original frame was then chopped into small chunks to stop it falling into the wrong hands. ) It could cause problems two bikes with the same frame number logged with the DVLA.
The Triumph chop is still being used it has changed hands many times and been MOTd many times, all you need is a fixed plate with the correct numbers easily seen and permanently affixed to the bike although to be honest it would look nicer with a pre printed Honda blank and just stamp your frame number onto it . Good luck try all the classic Japanese machine restorers or even the VJMCC for help.
