Thanks Dennis. I completely spaced that your boat has a 'T' section keel. I was thinking it had the 'V' section of the later boats, and wondering where you found someone to brake a part that long, and whether the ends were pressed or cut and welded.
Ray's comment about the gasket is right on point. Any significant heat in that area pretty much destroys whatever sealant is in the joint. ...ask me how I know.
The keel looks great! Nice job! (...that's what I should do to mine). Did you fabricate the new keel yourself and, if so, I'd be interested in seeing how you formed the tapered ends.
The tee extrusion is a little heavier stock than the original, but it was the closest thing I could find. I used a band saw to cut 3/16" off the bottom leg of the tee extrusion and the tapered ends. My tools of choice for smoothing rough edges is a belt sander and then various files.
The keel looks great, a BIG improvement in handling should result, from the description you gave from the previous, previous owner, I am guessing the hull was flexing and creating a moving hook. I am sure that was a hair raising ride!
On the dent, first is it leaking? Are you sure you really want to fix it?
On every Feather Craft I have worked on the transom sheeting is 0.093" and the sides and bottom sheeting is 0.050" and with the radiused form that has been worked into the transom sheet it is very ridged so I am pretty sure it will need to be heated and worked hot first.
Then I think the side sheet will need to be heated and shrunk to get it flat.
My concern would be that the seam gasket will just pretty much disintegrate and fall out during all this stressing of the seam.
I think I would take it out and see how it handles before I did anything.
Today I talked with the guy who owned this runabout prior to rivet-runner. The keel was in bad shape then. He said he only had it out once. When up to speed it rolled over to one side with the splash rail acting like a keel. Then all of a sudden it rolled to the other side. He said he about had to change pants.