Get new from scratch!
Old dodgers have a tendency to shrink and stretch and schoosh in various areas depending upon tension, sun, wear, etc. Have your choice of canvas maker come to your boat and make a pattern or take measurements for a brand new unit. Most shops that do that type of work have pattern on hand for most boats. I just had a dodger made for my new boat and I merely told the shop the brand and model. The dodger fit perfectly. I have had several dodgers and biminis made by the same shop with no problems.Jim