Tex, the "if it were me" answer is, I would open up a valley pan gasket to the size I needed, and I'd reuse it as many times as I could.
I would just keep replacing the paper gaskets after manifold R&R.

Andy's bat wing system might be easier to rework for your application.

Hughes has their own gaskets that are made to be opened up to facilitate ports in between std and mw size.