Re: Vire 7 Gas Engine
What boat? These engines were used in some of the smaller Bayfields, IIRC, and a few others including the Viking 28 by Ontario Yachts.
Chances are pretty long that you can get the Vire running, but if it's only a carb and you can find one (assuming it spins over still) it may be worth the effort. Certainly from an aesthetic point of view the boat will 'look' better without an outboard on the transom and she'll perform better under power in chop.
OTOH if you choose to stick with the OB I'd consider removing the original, creating more storage space (or an extra/bigger water tank could replace the weight) and get rid of the drag of the prop and shaft etc.
Option 3 would be to repower with a small diesel.. but you'd be unlikely to get your money out of that. Though that's not a big deal if this is going to be a longish-term 'keeper'..
To some extent this will depend largely on the boat in question.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)