I don't see that as being an OEM correct Q-jet.
The Volvo Penta OEM Q-jet would look like this one.
Note the different fuel line inlet orientation. Your T stat housing may not allow for this style.
Look closely at where the throttle shaft plate would connect to this shaft.
While the fuel inlet is different on this one also....., look at the piece that connects to the throttle shaft.
(circled in red)
This piece is capable of two 33C throttle cables.
You may have a Merc or OMC Q-jet.
The throttle cable bracket is also not Volvo Penta.... perhaps a Barr aftermarket bracket.
The OEM bracket would have also supported the ignition coil... and allowed for two 33C cables (dual station boats).
Your T stat housing is OMC I believe.
Your alternator mounting is likely also OMC.
Volvo Penta, during this engine model, did not mount the alternator in this location to my knowledge.
Let's hope that you have the crankshaft sea water pump.... and not the belt driven pump!!!!!!
Not a deal breaker....... but just make sure that the fuel metering is correct for the Marine Engine application.
Since parts have been swapped around some, be sure to check the distributor's advancing specs.
See the AQ260 OEM specs for ignition timing.......... and most importantly, the TA (total advance and RPM).
These MUST meet Marine Specs.... not Automotive!
You may damage the engine if these specs are not correct.
.