I think that they are. There are just some very unusual sizes in the lot.
The smallest I've ever seen are 28mm. Phil may have some of those in that lot and many of them are cut out of billet.
When Hall Pantera was selling complete Weber kits Gary was recommending installing 32mm venturi's in the carbs to "make them work like you expected them to feel".
I don't know about that. The 37's are pretty torque-ie but I never ran them on a box stock Q code Cleveland?
The bigger the throats, the higher the rpm torque range goes up.
The cast 40's are around. I thought I had a set but I was confusing that with my 42's.
I actually made a set of 40's on the lathe. They wound up being either 40.5 or 41's but finding the cast ones would be tough.
Try Gabriel David in Italy. If anyone has those, he would? Emphasize though that you want the Weber cast venturi's with the ID size cast into them.
What's good about dealing with him is first off, he doesn't rip you off like the US resellers do and second, you don't have to listen to him cursing you out because of the "strange" requests.
One thing I want to do is go to the nytrophil plastic floats. I've had so many Holley's have the brass floats collapse that I'm thinking it's only a matter of time with the Webers? Those he does not have.
One of the VW guys here in the US does but they just go on the wish list. Too many other priorities on the list above them.