I've been too busy to post on here lately. I still have the 2dr 710, but I finally sold the wagon a few months ago. As stupid as it sounds, I quickly spent all that money on the tools and parts needed to get my rusty 510 back on the road.
The only problem is the 510 looked like this in 2015, when I started the "re-build":
I knew I needed a donor chassis, so I looked into using a 1st or 2nd gen. Miata, S2000, Pontiac Solstice, or some exo-skeleton kit car
All of these options are at least 6-7" wider than a stock 510, so I made some relief cuts in the roof to bend out the roof pillars and widen the whole 510 three inches