Inlet manifold options

I have an iron 175 barrel on a S2 and managed to pick up a SH2/22 carb for it. Unfortunately the inlet manifold I bought has too short a neck and so the carb is unable to be pushed all the way on before fouling on the engine cowl and fuel tap. When I looked at the manifold I took off the 'neck' on the new one is about 2cm shorter - I believe it is for a GP. Does anyone know if it is possible to get a 22mm inlet manifold for a 175 barrel with the longer neck I need for a S2? Are there any other options or have I wasted my money on the carb!!!
Cheers
Tony

Cheers
Tony