Most Sail Lofts and Boat Top Makers...
should be able to help. Ask for references, or pix of their handiwork, preferably on the same or similar boat. There are enough OD25's around, the shop should have come across one. You have some choices available you may want to consider, including material (there are other fabrics besides Sunbrella), frame (stainless or aluminum), extra hand holds (some I've seen mount on the sides of the bimini), extra zippers (for dodger extensions or tieing into biminis), bug netting, etc. The boom sheet tackle is a consideration on our 25's, as is the placement of snaps or turn buttons, so I would recommend a visit to your boat from the canvass maker, unless they know this model well.Don