Welcome aboard.
Get a manual for the engine and drive from the respective companies
Most boat information is generic.
What information are you looking for? If you are looking for a manual for the boat, keep in mind there are no manuals for the boat
There are 7-10 different PRVs. Some are only 700psi, some are 2500 psi. The marine steering system is about 1100 psi. That is why you should reuse your PRV
and your stock volvo manifolds dont have any brackets. the brackets mount to the engine fasteners holding the manifolds to the motor
anything short of factory manifolds, you have to modify the brackets