I literally just order a New Merc stern drive gas 350 hp engine. I was seriously looking at Volvo. But the Volvo distribute was putting me through the ringer, finally got a multiple page document to fill out before they would sell me one. I was working through three different companies sort of locally. Each one said the same thing, we'll sell you the Volvo but we really recommend the Merc, parts are much more available, add on's are much more available, you can cruise just about anywhere here in BC and some one can work on your engine. They said Volvo will change parts, leading to shortages of what you are after, everything is more expensive, and less people can work on them.
At first I really wanted Volvo but now I'm much happier with the Merc I ordered. What I ordered included two new props (duoprop), harness, whatever else attachment stuff I needed, new leg along with the new motor.
The hole will be glassed in and a new whole cut out. The exhaust from the old Merc which was a twin exhaust will be filled in as the new engine and leg exhausts under water, something I really wanted. I was getting gaseous back fill into the cabin, not a good thing while underway.
I could purchase a new BMW with what this will cost me, but my boat is a 1969 and I have just bought some piece of mind. I knew I was in trouble when one of the guys looking the boat over for needed space etc for the new stuff said: "I've heard about these old Merc stern drive legs, but yours is the first one I've seen. Its massive. Parts for it will be difficult to impossible to get."