As stated above, the 1 3/4" SU can flow enough for some impressive HP figures. However, since the SU design is a variable venturi, this makes them, by nature, self adjusting for air and fuel flow. The problem that you might run into is whether or not the needles and piston springs are opitimized for the application. I can assure you that the engine will start and run, and you might not even notice the difference between the 2" and the 1 3/4". Since you're contemplating buying these off of e-bay, I feel you would be better off just looking for an 1 3/4" manifold. I just bought one a few weeks ago off e-bay for about $22...a whole lot cheaper then 2" SU's. They come up all the time on e-bay.