I'm not familiar with you particular boat.
I installed a prefabricated 80 gal fiberglass
tank in my bilge
for gravity fed grey water
. And I built in-situe another tank for the black water
by heavy glassing in around bulkhead and deep stringer like partitions.....installing the prefabbed one was way easier, but I was lucky to have a place for it.
The location may dictate the type of tank you choose.
In looking at locations, remember that you'll need to vent the tank and allow for emptying it.
Many people swear by having two vents coming from the tank to opposite sides of the boat, this is said to help the bio stuff work.
Emptying the tank can be done by pumping over the side or through a deck
outlet, or both.