Sorry for no pics or updates - I've been helping out the lake mates getting the slalom course ready and in - brownie points will be needed as I still have a lot of work and need others for pulls! I've also been looking through others' posts and learning a ton. Thanks again to this site for providing a wealth of information and confidence.
I've been making some progress at night - here's an update
The pylon has been chopped. I cut it at the base, just above the steel tube that is embedded in the fiberglass. I am going to stop at the local machine shop and inquire about a stainless replacement piece that has an ID of 2.5". The pylon OD is 2.5, so if I can sleeve the pylon with an "extended" bottom bracket, this might work out well.
I did some budgetary calcs on Seacast vs. stringer replacement and decided to go with the replacement route. Seacast/Nidacore was about $200 for 5 gals and I was looking at about 2x the cost. After cutting part of the secondary stringer on the port side, I decided to cut the whole stringer out and do the replacement.
The secondary stringer is out - I used an oscillating multi-tool - it worked awesome. Maybe a bit slow, but it created chips, not dust to blow all over the place and the flush cut blade made it easy to get close to the hull. After the stringer was out, the fiberglass was completely detached from the wood and the top half of the stringer just fell apart. The bottom was soaked in water.
I ordered medium cure epoxy from US Composites. Couldn't beat their price and the 7+ gallon kit looked like the right amount for the whole project. I'm planning to use 18oz roving to join the stringers to the hull - this is similar to the material that was used for the factory stringers. Two more layups of 8oz - 12" wide then 4" wide to reinforce the joint to hull.
I've taken measurements for the stringer positions based off the transom and centerline. I placed my laser level along the centerline and took note of the positions - I could see by eye that the stringers were NOT centered on the hull, so measuring this should be important. The engine is skewed to the port side. I had read in another thread that someone straightened everything out, but I suspected the MC did this for a reason. Another thread confirmed this - the skew of the drivetrain helps to counter the prop steer, so dimensions noted. I've got the entire engine manual for the alignment process, so hoping this goes well after repairing the stringers.
I've also blocked the trailer so the floor is level. This lets me get the height of the stringers right when I dry fit them. Because they are so rotted, I don't have a template, so I will be working a few nights to get the right shape.