Re: 1991 force 70 hp
Congrats on the boat purchase!
I have a 1992 Force 70hp on a 16' bassboat. Force had the same 70hp motor from 1991-1995, and my understanding is that they called the same motor a 75hp in 1996 and 1997. My experience so far has been really, really good, and I've owned my boat for about 10 years now.. Even let mine sit unattended in the weeds for about 4yrs and dragged it out a few weeks ago...fresh fuel, fresh battery...fired right up.
There's no tell-tale (pee hole...pee stream...etc) on my engine, and probably not on yours either. That's just an indicator anyway, though.. The cooling water is pumped out through the prop hub.. If you start it on a hose w/ 'earmuffs' in the driveway, you should see it begin pumping water through the prop hub almost immediately once you start it up.
Now, having said that...probably not a bad idea to visually inspect the impeller before you start it up if it hasn't been run in a while. I don't know if that's the case or not, but a dry-rotten impeller can shed vanes really quickly, and you may end up with chunks of rubber hung up in your water jackets.. That's not a *likely* scenario, but pulling the lower unit and checking the impeller is really easily done on these engines. After being asleep so long, I checked mine visually before even turning it over.
Oddly enough, the impeller was fine and I'd never changed it.. It's been in there *at least* 10 years and it was just as pliable and rubbery as new...lol