Attached is a PDF file of the overall dimensions of the cushions in our C-22. There are a few fine points to watch out for. Only the seat back cushions are strictly rectangular. All of the other cushions have one or more tapered sides to fit the hull curvature. Also, the curved cuts of the V berth cushions are also tapered vertically to fit the hull taper. Otherwise, you will get a gap there. So use these dimensions for estimating purposes and if you don't have some of the cushions already, make an accurate pattern for the best fit. These dimensions could also be +/- a half inch here or there from the original design due to the factory cuts of the foam, which wander a little bit.
Another issue to consider is the table top cushion. The stock cushion's inboard edge aligns with the forward seat cushion edge. I'm cutting ours several inches longer to completely cover the table top and to align with the aft seat cushion corner and the inboard edge of the keel trunk. This makes it fit together better with the other cushions to make a full-width bed in the settee area. Along with that, I'm making an 11th cushion to cover the step and finish the "puzzle."
I hope this helps somebody. If you need more information, PM me and I'll do what I can to help.
Enjoy!