I personally would take care of the blistering, re-gel, then barrier and bottom paint
However it is your boat. its up to you.
Since the boat is well past its design life, I would also entertain just using it as is and tossing the boat in a few years.
typically if you are mooring
2-3 coats of barrier coat followed by 2-3 coats of bottom paint
the barrier coat protects the gel/fiberglass from blistering
the bottom paint protects the barrier coat
I use beer and applejuice (no brine) for my smoked bird
smoker gets fired up at 8am tomorrow
will be 10# smoked bird, 22# oven roasted bird for 7 people.
food coma and stretchy pants
that is only the idle circuit.
I would start by changing the fuel filter and pour the contents into a clear container. you may have water in your fuel which would cause you to run lean
half system or full system? my guess half system
change oil and filter
drain the line from the drive to the PS cooler to the HX
drain the two manifolds
pull covers off of HX and clean out the water side debris
true pumps from Carter / airtex will be about $200 (cut out the middle man as Volvo has a 500%-600% markup to put the carter pumps into a volvo box.
HP should be P61171 (you will have to verify)
LP could be P61122 (you will have to verify)