We have a 1979 CT41
ketch that came with a 75 hp MD21A
Volvo Penta engine. It ran well (except for having to replace the
fuel injection pump - twice - due to fine rust from the black iron
fuel tanks making it through the filters into the engine. We replaced the engine.......not because of the injection pump......though that was difficult enough, but because when the fresh
water pump started leaking....we couldn't get
parts. Anywhere. And as we worked to remove it, bolts kept breaking. Too much
corrosion.
We replaced it with a
Yanmar. Replacing an engine is such a pain......I can't imagine in your case that another, used, Volvo, was used.
Consider the possibility (likelihood) that you'll have to replace the engine, and check out the fuel
tanks. Ours were under the settees, relatively easily removed, and we had
replacements made of aluminum.
It can be done. If you love the boat..........