I was the one with the talon and the lag bolts on the bottom. Yep, the idiots, in my opinion, drilled two 3/8 holes in the hull and put two 2.5 inch lag bolts in completely thru the transom below the water line. You would think they would have used about an inch long lag bolt and not go all the way thru. In order to put the talon on, they had to move the ladder over. It looks like they just filled the original holes in with a small screw with silicone all over it.
It it were me, I would use the thru hull bolts on the top bracket but the bottom one, you are pretty much stuck with a lag or wood screw type fastener.
I have a 621FS.