I don't make them, that's what they told me. They're the professionals. It would be good to ask someone that has a 2 carb setup how it runs. How he tuned it and if he's content with it. I've seen it done many a time. Im not an expert, but ive seen Chevy 350's with 500 cfm 600 cfm 700 cfm up to 900 cfm carbs. It doesn't mean its specifically tailored to that specific engine, but im sure its close enough. I have a friend with a 366 Chevy engine (I had never heard of it either) with 2 progressively connected 600cfm carbs, he says he wants to go to a single carb 900+cfm Carb because though it does give him crazy performance, the in town usability suffers, that's a 300cfm difference but im sure its going to run great, I doubt anybody would criticize him on not having the exact perfect carb for his engine . 235 and a 261 engines are not precision modern machines (though in their time they were), im sure Rochesters and these UN2 units can be adjusted to give adequate smooth performance as ive seen done with mine (and im still tinkering with it). I cant come to grips with some peoples opinion that the carb has to be perfect to that engine. In that case, there would be no aftermarket carburetor dealers, Edelbrock, Holley, Demon, and who knows how many others.