Ok here's what I've done so far.

Decided to got he seacast route. Not for any other reason except I'm not real comfortable hacking the back off my boat.

Spoke to seacast again and I decided to chainsaw the wood out from the top.
I guess when you spend your Saturday chainsawing your boat with your brother over a couple of beers you officially qualify as "White Trash" but I'm going for it.

We quit about 7:00 PM and have about 80% of the wood out. I was a little surprised how easy it was. Not that it was easy but the mere sounds of it was a little scary.
Dropped the motor and all the stuff included, removed the cap, stainless plates and everything else bolted to the transom including all three drain tubes (2 scuppers and the bilge drain).

Got a 25" bar for my chainsaw, built a scaffold so we were at a decent height to work. Didn't poke any holes in the skin and it still maintains it's curved shape. Getting all the wood out is not to bad as long as you take your time and trim the sides with the saw, right down to glass.
I'm not going with the bracket and full transom.

Problems so far:
1. I need to fill the wings with seacast but because the transom is under the gunnels, I'm going to have to cut the gunnels and patch them up later.
2. the skin developed holes over time where the stringers (not sure if you call them that with an outboard set up) extend to the transom. Going to have to go into the bilge and glass the hole up before the seacast is poured in or it will fill the bilge before it fills the transom.
3. What exactly do these "stringers" do? My deck is solid as a rock and they don't seem to do much to support the transom. There is some rot at the end of them but I don't plan on ripping the deck off to fix them. Mistake???

The original V 20 setup is for a 20" shaft with a cutout transom at the outboard only, mine is set up for a 25" shaft which means someone filled the transom cut out. I'm going to glass the cut out back up to the new height as per Seacast instructions.

I've got pics of the process so far and I'll post them if I can get setup in the Gallery again.
I don't know how this boat hasn't sunk yet. The plywood was about 90% rotten. At some points it actually looked like mud. Worm dirt would have been a good part of it.

We'll see what tomorrow brings, but I should be ready by the end of the day to glass the cut out and get ready for the seacast.
I'll keep you posted.
Thank you everyone for your ideas and support.

Mike