Dunno. A Norvin used the repopped Vincent engine coupled to a Norton frame. It was affordable to ordinary mortals, but still expensive.
Here in Australia Vincent engines were fairly cheap in the 60's. Lots were used in speedway outfits.The Norvin was an English late 60's early 70's creation in the main when old Norton wide line frames and Vincent engines were't worth a whole lot. Plenty of engineeringly talented rockers and cafe racers of the day put them together.
I was chatting to a spectator at the Classic that was riding an old 850T3 same as my brothers in law rode back in the 80's. Yes 2 brothers in law each with an 850T, one a T and the other a T3. This guy has an old Vincent series C Rapide at home he inherited from his late father and also some other Vincent bits to build another bike. He was short of a crankcase half though but managed to pick up a battered second hand one for $3000au from an ex speedway outfit that needs plenty of work and machining if its going to be matched to the half he already has. Not cheap to join the Vincent world.
Ciao