Never found a case where the stringers are exact copies of one another, good to see you were able to pull the existing to use as a template. Minor differences exist due to variability I believe in the fiberglass process. I've not found the hulls to have differences, but inside does seem to change. A bit of massaging will be required to get a proper fit. As for the foam, the old stuff is not waterproof, but if has not absorbed water yet, it probably can be reused. New foam technology is harder and waterproof, will not absorb any water unless it is cut or damaged. Holding old and new together in your hands, it really is different stuff. Bad side is the cost, replacing all with new foam is probably is pricey. Always shoot to pour around 80 degrees if using the new foam, in that way you get the maximum expansion and acceptable working time. closer to 90 degrees, you gotta move fast. Below 80, say 60, the foam will not occupy as much space. Great to see progress, hope you make it out on the water this year.