My 30 has very similar construction, I removed the liner and put a solid deck floor, are you doing the same? I was surprised at the incredibly crappy construction of mine, there was no support from gas tank stingers to next stringer beside it, and I must have got a Friday afternoon boat as there were little bitty supports going from the outside stringer to the side of boat BUT they were fiberglassd to side of hull but had masking tape holding them on to the stringer. And under the liner was a ball of fiberglass and resin with a mixing stick stuck to it, I guess the builder thought no one was ever going to see it. I have since completely made it much more structurally sound with lots of cross bracing and solid deck.

Yes I like the crank mounted pumps, easy impeller change and they do flow a lot I have never had cooling issues with them, I also don’t use stock pullies, I run the largest crank pulley and smallest water pump pulley and Stewart components stage 3 water pumps, I do have heat exchangers with antifreeze as I run aluminum heads on my motors.

Once I have all the stringers glassed in I plan on a 1/2" plywood floor with some glass on top of that.

I found a LOT of air bubbles in the bottom that I ground down before adding the 2 layers of glass.

The top of the old transom wood was like 3-4" short of the top of the transom step and there was like a 3"x3"x60" void of just air. Kinda hard to describe but I made the transom wood much taller and left no air voids. The ones I had left i filled with thickened resin.

Under the bilge "liner" was a minimum of 200 pounds of what I would describe as roofing tar to hold the liner in place. That was NOT fun to grind out

Why not just buy 14 inch flywheels, Sbc are either internal or external balanced, all stock 350 are internal balance
so just buy a cheap 14 inch flywheel, later vp engines used the 14 inch, I don’t know how merc couplers work but
all Sbc/bbc flywheels have same bolt pattern. My 388 sbc are using bbc 12 3/4 external balanced flywheels.

On your exhaust, yes you can plug that hole and just feed water from bottom of manifold,
replace all the gaskets between the spacers, also looks like your risers point down, may need to replace
them, I ditched my cast iron beasts and bought some Barr marine generic Sbc aluminum manifolds.

The pre alpha coupler from the old engines that bolts directly to the crank bolt pattern did not match the crank bolt pattern on my current engines. That's why I ordered the alpha1 coupler that bolts to the flywheel and not the crank bolt pattern. The 4 cylinder mercruiser coupler should solve all my problems other than having to clearance the bellhousing.

Started fabricating some silent choice diverters

Nice

Engines out, fuel tank in. The stringer grid is getting close to finalized. Now we just need some warm weather up here in the north so I can start glassing. Unfortunately my barn is not heated or insulated yet.

Wow nice work