Sam what seems a hundred years ago I ran a pair of Weber IDA-3 carbs on my PRV six.... I purchased the manifolds out of the UK.
I suggest 45mm carbs.... More compression and cam...
They will well and truly
YELL!! at wide open throttle.
Watch out for ice developing on the throttle plates while driving in cool damp weather.... This will make for the throttle sticking open at light load.... To the driver this is not amusing! At least at first
I've seen throttle bodies that allow programmable management that bolt in place of IDA-3 carbs..... Programmable engine management is fantastic.