Ok, I got the scoop from Seacast via a phone call today. They were real helpful. I uncap the top of the transom first. Than most people use a chainsaw, some use a drill bit, and basically whatever works to remove all the wood. Now to answer seakindly's question: If there is only a small layer of plywood still stuck to the fiberglass, leave it. She said it would still have a lot of resin on it and it would be safe to leave and would bond fined with the seacast.
My next question is this:
Do I raise the transom to the gunnel hight and install an outboard bracket? I've always wanted one with a swim platform like Stainless Marine's model.

If I do this what will happen to my Center of Gravity? My scuppers are already below water level. Will hanging the outboard another 18" back change that much?
I need to pull another steering cable, but all my wiring looks to have enough slack to work. Any other drawbacks?

I wonder how long all this is going to take?
I figure probably a good two full days to get rid of the wood transom, a day to glass the extended hight part and a day to pour the seacast (even though its about a 1/2 hour job. I wouldn't mind but its not really that expensive.

Any thoughts??

Mike