Based on OP pics/comments it seems to me the boat in question is more of a "let's just make it work" vessel than a legit, sound, factory spec vessel. Just my opinion, tho
IME if I see something suspect on a boat/marine engine it often times is something not correct, i.e. unsafe. AFAIK Volvo never produced oem a Ford engine branded SX package that was not efi. And these Ford engine based packages were only offered during the OMC/Volvo crossover years.
Some red flags I see are the MSD ignition, Holley carb that may not be marine rated, and as mentioned, additional guages.
I'm not saying the engine package isn't marine rated, however there appear to be at least some instances of added components that may not be marine rated
OP, do yourself a favor. Based on your admitted limited knowledge of safe boating equipment, find a local, reputable marine reapir shop to at least give your boat a decent once over for any safety/necessary issues. Don't find out the wrong way. Good luck