Everything Bill R said, and then some...
If I was in the market for a new genoa, I would immediately be concerned if I was asked what size genoa I wanted (130, 140, 150, etc). If the sailmaker did not know what the size of the original sail was for this boat, I would find someone who did.
At some point I would be sure to ask how the sail they intended to build would work with the Amel downwind poles. If they did not understand how those poles work, and did not know the sizes of the poles, I would go somewhere else. There is more to an Amel genoa than just size. For example, the clew has to be at the right height for the downwind rig to work as it was designed. I know this thread started with questions about upwind work, but we do a LOT more miles downwind than we do close hauled so downwind performance is important to me.
It is likely a tall order to expect a random sailmaker to have a detailed understanding of how a Super Maramu is different from other boats they make sails for, and why just running off the dimensions in their rig database is NOT the right answer. It is a tall order, but it is one I'll insist on.
When I needed a new ballooner, I talked to several lofts, and got a LOT of responses that were some version of, "You need a WHAT?" That would pretty much be the end of our discussion.
Great Guana Cay, Abacos, Bahamas