I know lots of people dislike people asking questions, then never updating results...well, took another year, but I finally got back to this project.
Turned out swapping those T&T units was a LOT simpler than I expected. Didn't even have to touch the bit pivot bolt, just pulled the all parts in between the two large "horseshoe" shaped mounting brackets. All the holes were already present on the motor getting the T&T unit, and I only had to run a thread chaser to break out the paint on the threaded holes.
Pretty sure I could have done it with the motor still hung on the transom if I really had to, but I have a large crane mounted to my service truck, and why make things hard when you don't have to?
All in all, took about 30 minutes to swap it all over, and works great...in the driveway at least. Still working through some carb issues (pretty sure it was just old gas), but fingers crossed this thing will be in the water this weekend for the first time in a LONG time.