Hi Peter,
It ended up as you said. Full aft on the deck ring = old mast deck ring location, and the mast butt ended up being moved forward 50mm/2 inches. I haven’t got the boat all back together yet, finishing up the paint, but the numbers match other late model boats so I think I’ll be okay. I have a ton of adjustment in the mast step, probably 4 inches. Thanks for your reply.