The OMC steering cable was already loose when I got the boat. Do you have a picture of the bolt area? Maybe I can look on my old parts to get an idea.
My cost is with me doing all the work except that I am having any media blasting and powder coating done by others. I did have to buy a lot of parts that did not come with the boat which is what you face in switching from OMC to Merc. A lot of my cost is buying new parts to replace old bad ones for the Alpha drive plus the cost of marine plywood and lots of fiberglass cloth and resin. I did have a guy glass in my new two layer marine plywood transom and fill the old OMC hole in the hull.
The other cost is in the engine build with the machine shop doing that machining and I bought new pistons and rings, new oil pump, new oil pan, roller marine cam, roller lifters, roller tip rockers, and new pushrods. I went with new HGE dry joint exhaust manifolds and risers and the Monitor Products closed cooling system.
So, mine is a full restoration though. I even disassembled the windows and powder coated the frames as well as removed the rub rail and had it powder coated. I still need to buy new insert for the rub rail.