I'm helping someone do this to another boat and it's not a hard rework. You will need 1/16 aircraft ply for the skin, a block of 3/16 or 1/4 aircraft ply for a strut doubler and some spruce stick stock to make glue blocks from. Size will be determined by any damage to the framing when taking the boat bottom off. I would go to
www.rossisales.com and get new hardware from Speedmaster. They can help you pick out the right parts, just be sure to get the left side rudder assembly as it's normally better to pull the rudder to turn than to push it