So from the photos you can see I cut out the rectangle of ugliness under my battery tray. To repair this I see two options, but since I'm a newb I'm not sure which would be better:
Option 1: Buy a repro apron, cut out a square and weld it in. Pros, the battery tray mounting holes and associated under-tray strengthening metal will be there, all I have to do is cut the patch correctly so the tray mounting holes are in the correct location. Cons, that last bit in the "pros" where the patch has to be cut just right so the tray mounting holes are in the right place, and it's hard to tell the quality of the repro apron. (Sounds like Canadian is NOT the way to go with the apron)
Option 2: I just saw that NPD offers just the reinforcement plate for under the apron, taking this route means I weld in a piece of flat steel to fill the hole, then can use the battery tray to easily locate and drill the two mounting holes, then weld the NPD strengthening plate on the bottom with its holes aligned to the battery tray holes drilled in the apron. I'm not sure if there's really a "cons" for this other than it's more welding.
Here's a link to the NPD tray reinforcement: http://www.npdlink.com/store/product...p_by_year=1967
So which is better, or easier etc. A repro apron costs about the same as the NPD "concourse correct" strengthening plate so cost is a wash.