A little update..
I ended up buying brand new oem mercruiser manifolds and risers. Got them for $650 shipped.
Put my jrmarine repaired gimble ring in, the whole assembly has new seals, pins, bellows and all
Everything was going good, until I went to torque down the transom plate. Used 25ftlbs as specified. Got to the lower bolts and...crack! Plate cracked. After investigating, I have a soft transom. Great! Rinker failed to use anything to water proof the bottom of the wood. This picture is at the bottom of the bilge looking up. Wtf?!?
So, got the wood removed. Luckily the wood is just this section. Doesn't go to the stringers.
Made a template of the wood before I took it out. Today's plan is to hunt down some replacement wood and start cutting. Been talking to a place in California for the fiberglass supplies. Hope to have it all back together in a week or so.
Back on topic though.... I may never have really found exactly what happend, but I think I am doing a good job of covering my arse. New raw water pump, new engine with new water pump, all new hoses, new manifolds and risers, nrw shutter valves for the y pipe. If I'm missing something, let me know.