On the 72-76 stampings-the only company I would consider buying panels from is TABCO out of Ohio.
Problem is, right now, they have yet to do another run of quarters for either side, and it's be atleast a solid year since I asked them if they had any on hand.
I am assuming you got panels off ebay?
I saw those, and they look...well, not to be rude, but not what I would use.
I drove out to Ohio and got a tabco stamped panel. thick metal, zinc coated, panel would not twist end to end.
I have another 1/4 panel I got also out in Ohio on the same trip, and it was an imported stamped piece. you can take and twist the panel, and it's thin metal. Stamping lines were acceptable to me, but the thinness was not really what I like at all.
The old adage goes you get what you pay for.
Hey Ryan, PM me.
A guy I know bought a bunch of Elite stuff of me a while back, and he may have quarters I sold him that were ok.
Keep in mind, for the lowers off like a 4 door, they will work to patch an Elite.
The big problem has been the wheelhouse, and I found using a modified 71-73 mustang wheelhouse will work better than fabbing from scratch:
