It's a lot of work, but not brain surgery. The hardest part for the home do'er will be getting the engine
in and out to predict the angle of the stern tube etc. (unless you've got a removeable panel in ther cockpit
floor) You will likely want to lay everything out, put in your engine bed
(Not fully glassed yet), put the engine in and determine the hole location for the stern tube. Cut the hole and insert the tube/cutlass/stuffingbox assembly. Then put the prop shaft through the tube and mount to the engine. Also check that the predicted angle of your engine bed
is going to allow alignment/ motor
mount adjustment. Lightly tab the stern tube in place, maybe just using kitty hair to fill the gap from the outside. Let it harden. At the same time go outside and, using the strut on the prop shaft, determine where you need to build up a pad to mount the strut on.
Now remove everything you just did including the engine etc and do your glass work. You'll then reinstall everything and check again!...and there's more , but you get the gist of how much work it is....