In your area there should be more than one canvas shop that can do what you describe, and it doesn't necessarily have to be "marine" canvas. RV and automotive upholsterers are certainly capable of duplicating pieces and sections and sewing them together. When it comes to this kind of work, the high cost is in design, building and installation of the frame. Then, of course, the design, measuring, cutting and installation of the covering. Which will require a number of trips between shop and boat. Here, you're not asking the craftsman to design or install, or even travel........just duplicate. Because you've stated that you are capable of re installing the new.
But, by far the most difficult part of building a dodger is getting everything to fit properly... and that's why they cost so damn much money... because every boat and every design are just a little different. But.... Yippee.... you alread have the pieces/patterns that fit your boat.. so... the hard part is done. There isn't a canvas shop anywhere that won't jump at the opportunity to make money that easily.
So.., take some pics of everything, including the pieces you DON'T want made, so they can see how the new parts will integrate with the old, then assemble a portfolio with a letter stating your needs and ask for recommendations for modern upgrades, such as glass, thread and canvas quality. Trim material has changed over the years, they no longer use leather, but a much tougher, longer lasting synthetic material. Anyway, make some copies and send out the package to at least 7 or 8 shops and ask for bids. Choose the one you feel most comfortable with and the least flakey.
