If not a part number, how about a model and year? Not the ones with fuel pumps, of course.

I tried searching, but I suspect the info is somewhere on the other side of 100 search results. Or I just don't know the magic combination of search words.

¡Gracias, amigo!

If you look at the drawing on the fische, you see there are a short and long tube that go in the tank. The short tube is the outlet for reserve. As long as a petcock has a reserve setting, you have reserve, regardless of the tank. How much reserve you have depends on petcock location and the shape of the tank.

What you don't have with a non-vacuum petcock like the one from the Raptor is separate on and prime settings. On works like prime. The up side is that you always have full flow when the petcock is on. The down side is that you always have full flow, even when you don't need it. That means your floats and float needle valve are all that's regulating the flow of fuel from the tank. Get a piece of grit lodged in the needle valve, or have your floats adjusted wrong, and you get too much gas. And it means you must always always always remember to turn off the petcock when you shut down the engine.

I don't have a Raptor petcock to look at, but maybe reserve can be increased with a little modification to the intake tubes. Of course, since tank volume is the same, increased reserve means decreased main capacity.