There's nothing Volvo there, that is all OMC. The 5.7, with newer style center riser exhaust manifolds instead of the original log style manifolds and a dog clutch OMC Cobra outdrive, as produced from 1986-1993. Not sure on the exact year but I know from looking at the parts diagrams that the exhaust changed in '89, another change was switching from the Rochester Quadrajet carb to the Holley. Looking at the pic of the engine from the front, the fuel like looks like the Holley to me, so that would make it a '90 or newer. The only way to tell for sure is if you have the model # which is usually on a sticker on the thermostat housing or the valve cover. Looking through the Crowley Marine parts catalog this combination was used in '90, '91 and '92. So it's one of those years....While the boat is a '93 it is very possible to have an engine package that is a year older, so it could well be a '92.
This has what looks like a spread bore Holley 4175 4bbl carb (parts are all available, so rebuilds are not really a problem, and new 4175s are available. The distributor is electronic unlike the earlier models that had points. The exhaust manifolds and elbows are available in the aftermarket (same as Volvo V8 parts) and most parts are available for the common style dog clutch Cobra. The only item I can see that might be an issue is the ignition module which is NLA but I bet you could convert the distributor to a Delco EST if the module ever when bad.
