I use the pick up truck type of davit Brent illustrates for my Duroboat. Its weight is about 300 lbs--and I have an Armstrong electric which (no relation to the bracket)--the lower pipe which takes the load, is heavy tubing. Yes, you could make a similar type of davit for the outboard bracket on the Tom Cat. One problem might be the thickness of the top deck of the Armstrong bracket--you can resolve this problem with a backing plate if necessary. The other problem would be metals. You can use aluminum--but most of these are steel--some are glavanized. You would have to isolate this from the aluminum bracket--and keep it free of rust. You could go the real expensive way--and make it out of Stainless (I did this on the Cal 46 and had a davit to lift 150 lb outboards with--very simlar to what you illustrated, but it had a tubing mout welded to the base of a large radar arch on the stern of the Boat. All it takes is $$--and the space on the bracket. Most of use use what is available, but for example I had the bracket for the base which mounts on the cabin side for the Garhauer at a local machine shop for about $65. Lots of machine shops will will make anything which you can dream up.
Getting back to the original concept of this post, If I was making the turn over type of system, I would make a frame work--winch the boat up to the framework and then flip the entire framework, rather than just two hoisting points and gin poles--but the issue becomes weight--SS looks nicest--but aluminum can be a bit lighter (but has to be heavier guage to take the loads).