What engine do you have in there now? I had a 1977 E27 with the original A4 so there were some changes needed. The A4 had a 3/4" prop shaft with the diesel I increased that to 1", which meant new shaft, stuffing box, and prop. Had to put a larger cutlass bearing in but only the bearing itself, the strut took a 1" bearing just fine.
For the engine bed I had to add some Ash risers, about 2 1/4" thick I think, maybe 2 1/2" and about 4" wide. Bolted and 5200 those to the existing bed to get the engine high enough to align the shaft. That meant I had to raise the wood engine compartment cover about 1" to clear the new engine (added soundproofing at the same time).
As I remember the engine controls worked backwards from the A4 so had to redo all those. Got to keep the original Aluminum fuel tank though, just rinsed it out and added a fuel return line to it.
Of course had do some doctoring on the exhaust to get it to run right. Also added a red dot cabin heater to the cooling system while I was at it.
A few years after I also figured out I needed to change the raw water through hull to a larger size. The original was pretty tiny ID. While it cooled the engine OK, the increased velocity through the small opening kept sucking up kelp and clogging my strainer. Sometimes in the fall around here it got pretty bad.
Other than that, piece of cake ; ) I did all the work myself so by the time I was done knew everything inside and out. But it was worth it for 20 years of care free operation. As I said, a great little engine.
Here's a pic to see if it is the same one you have. You can see the risers I added to the bed.
Kevin Wright
E35 Hydro Therapy