So, we put the boat away in the fall of 2010, and didn't run it for the 2011 season (here in PA). (Trying to save $ for a new house).... turned out I just blew through 3 engines in my jet ski that summer instead).
(but that's another story).

It was properly winterized, oil changed, etc. (Gear gase oil, engine oil, fuel stabilizer, block drained then filled with antifreeze)

Only issue may be the multi year old battery.

What else should I look for?

I don't know the hours, but my wife and I keep this thing in 110% shape. Every bolt / nut / sticker is religiously maintained.

It's a carb, should I buy some starting fluid in case? It's never given us a day of trouble in 20+ years of service (ONE starter and ONE water impeller).

It's a OMC King Cobra 460.

thanks. I plan to head up with a vaccum, some tools, battery charger, and anything suggested here...

I put new plugs and wires in it in 2009, not that the old ones were bad, but they were pushing 20 years old...

I'm fairly handy with a wrench, and if that fails, a hammer, so let me know what to check. I think I have carb cleaner in stock as well, since I used that on my ski's for the last rebuild. (I wasn't the one rebuilding my engine for the 3x it blew in my ski). (Found a new shop w/warranty now).

Sitting for a year and being properly put away there shouldnt be any problem at all. Did you fog it when you winterized it?

Charge up the battery, put some fresh gas in it and Run it for a few minutes then change the oil.

Yes, it was fogged. The oil in it was never actually used, just ran for 5 min while fogging it out.

Gas tank is full.

Charge the battery and turn the key...