I'm happy enough now with the covers, finished up over the weekend. They cover all the way out to the body seam nicely and will do a better job than the original covers, or the proper covers on a plus car, IMHO. Granted the most professional look would be to score the wider and deeper covers for a 62 pack, along with the pack, if you're lucky.
The 24-40 pack covers are not as wider along the sides (wider forward side mounting flanges on the 62 pack), so they don't cover out as far, and don't lay flat on the outboard edges, nor reach the outboard cover mounting holes on the 62 pack. So the outboard edges hang down (at first, in the earlier pictures).
Some of the mounting bolt and pushpin holes line up at the front and rear edges of the pack, between my original covers and the 62 pack. In the middle areas of the pack, I drilled extra holes in the covers to line up with mounting spots on the battery.
The front battery cover would fit just about fine, except for the low cowcatcher I added in front of the battery. I was able to bolt the rear of the cover to the original mounting points at the front of the battery, and bend the cover under the cowcatcher bar and up to the forward cover mount points. The front of the cover is secured with zipties instead of pushpins, since it doesn't quite reach that now longer distance.
After getting the existing covers on to this point, I made additional covering along the sides. These hold up the edge of the original battery covers, and reach all the way out to the body seam. White coroplast was available, and some other metal bits to hold that up, using existing holes along the battery mounting flange, and an extra hole at the front and rear. The side covers also take care of the narrower section of the forward battery cover, ramping down over the cowcatcher bar. Maybe I'll spray can the covers black when it's warm out. Or make a better version of it, after seeing how these work out. Even as is, it looks fine beyond a few feet away. At arms length, then it looks a little homemade.
There's definitely lower ground clearance! I didn't measure, but about 4-5 inches I guess. I also didn't measure trim heights before and after, but it looks like closer fender gaps than before. Sporty! I can take lowering springs off the wish list.
Maybe some larger wheel & tire set would get better ground clearance and fill up the fenders better.
Added pictures of the covers here: https://photos.app.goo.gl/tcVLm3SHCtozeLSa6