depends if you have a water activated choke or a manual one....
manual choke best option would be a regata 85s carb (1985ish), or similar, these run a 32/34 dmtr type carb, which in addition to being slightly larger venturi and throttle blade sizes, has brass bushes on the throttle shafts, as opposed to nylon bushings (which is probably whats worn away) in the std X19 carbs
Other cars to look at would be the Lancia range, including the twin cam betas, as they use the same style of carb, only larger internals for engines all the way up to 2litres...
I'm sure you can find something.... I have seen a couple of new carbs on Ebay in just the last couple of days.... check german ebay, theres a brand new carb in there
SteveC