These guys are not in NY, but they had all the dimensions of the C36MK((. They produced beautiful cushions for us. The design includes a mesh vinyl fabric that is much easier to clean than solid vinyl. The cushions can also serve as flotation devices. We purchased in 2013. Hopefully, they are still around.

Ameriseam
Marine Canvas
13801 Hillsborough Ave
Tampa FL
813-854-1128 

I ordered new cockpit cushions from Ameriseam earlier this year. As mentioned, they have the patterns on hand so the process was simple, quick and probably less expensive than someone having to pattern and do a custom job.
The standard cushions are 2 inches thick but seem pretty hard, if doing it again I'd ask for 3 inches or softer foam. That said I got what i asked for and Ameriseam did a good job at a fair price.

Got mine from Catalina Direct.