Getting ahead of rim leaks, bead leaks, bad seating area

Well, after a decade of likely running solid filled tires, the rims are in a bit of rough shape. JD 644E

So, there is some pitting on the rim flange area, pits maybe a 16th to an 8th deep. Trying to guess where everything seats is a little tricky, there is a 3 piece rim, so the o-ring groove is pretty pristine as is the inside of the rim piece. The flange rings fit nicely on the rim, good solid looking, replaced one lock ring that was damaged. It looks like there is a 1 inch smooth area between the flange and the ribs inside the rim. It seems this should be tapered like the inside slope of the rim, maybe a 2-3 degree angle and there is a smooth part of the tire with a small bulge right next to the support ring. My plan is simply to primer the rims, bondo up the imperfections, primer and paint over the bondo to have a nice smooth surface in order to give the tire a chance to seal. I'm not quite sure if the area should be 0 degrees but it looks like it should have a bit of taper to make a nice wedge seal.

Anyone have any great tips for making sure rims seal and stay sealed.