Is the TRS transom cut out of a size and shape that it can be enlarged to take a Bravo TA...or does it need to be filled and re-cut?

It would need to be filled and recut. However merc makes a conversion plate which was designed to cover the large hole of a Volvo for converting to a Bravo. From what I hear these will also work to convert from a TRS to Bravo. They aint cheap but probably cheaper and cleaner than reworking your transom. Part number is #827691A1. Check around on the net and you will find them priced between $950-$1300.
http://www.marinepowerservice.com/Bo...ctID/44828.cfm

That would be definitely less drama for sure.

$150 in plywood, 500 in glass and resin, some serious elbow grease to do it right.....

I had some plates made I use them on the race boat. Work great shoot me an email I will send pix I have about 300 bucks into them if you want 1

post some pics,i am interested.

I got the budget membership
Send me email I will send for you to post

Send them to me [email protected]. I'll post them.

Did that before with a plate.I used a piece of 5/8 alum plate.Cut it to a size that covered the the trs cut out and holes,basically the out line of a trs transom assemblie.Marked out the holes from the trs along with the shaft center.Then took the bravo pattern along with the shaft center.Centered both centers with each other then marked the bravo holes.Drilled all of the holes.The center hole Was used align both sets of holes. Took the old trs pattern holes filed them square.Used stainless carriage head bolts to attach back to the transom trs holes.You have to trim out aluminum in the center of the plate so the bravo transom assemble will fit in flat.Then bolted it all up.You will have to use some spacers inside to make the inside transom plate even with the existing transom.I left the original X dimension.But you could raise or lower the X dimension if needed.But most of the time when you go to make this change the transom is rotten,so it is easier to fix re glass and cut the new hole JOHN SR