The right rail can be pulled in at the front to meet the tip, but it would be better to bump some stress-relief out the side of the fender first.
I believe these are OEM trim bolts. (left) front (right) rear T-bolt
What's this tab? For a later year? It's not for the brake tube clamp. The brake tube clamp hole, is 10-32, and tapped into the laminate of the side mount braces.
Front tip has relief indented that requires you to use a longer mount screw for the top hole in the tip. The holes match up perfectly to OEM and AM tips. Two screws are used at 12 and 6 o'clock on the '59-up tip. Middle hole is for a later tip maybe. I think the holes are also good for the '49-57 tip as well. I'll try it and see.
I'm flooding behind the brackets with brake cleaner spray, then flooding the same with DP-90 primer, wipe off the dregs and let it dry. Doing the same with the topcoat, to try and minimize future rust.