Been looking out for project stuff and not found much but came across an almost new Vespa gts125 complete rear end for a good price.apart from the obvious what bikes could this fit into without too much bother (looking at Vespa px bare frame with v5)
Not sure if it’s relevant but there’s a fairly active scooter racing scene. They race with the British Historic Racing club. Can imagine they’d have done all cool engine swaps and stuff so may be worth a look?