This is where the tricky part comes in. You will have to check out the carbs to see at what angle they must be put on the intake runners to let the floats,etc on the carbs work without problems.
Bike engines tend to be at a slight angle to the front part of the frame. So I would think the bike carbs will also have to be at an angle towards the engine. That is why I would suggest check out bikes at a scrapyard to see what the angle must be + - not to make a mess of it.

Please mail me your setup's pics. I am really tempted to do the same but with fuel injection.