Thanks for the kind words guys. She's going to be pretty sweet once finished. I've got another project up my sleeve that I'll be starting once the rear end is all back together. Should be a lot less ridiculous fab on the next project and a lot of readily obtainable bolt on parts. Pretty excited for that. Updates on that once the arms are done and the 510 is back on the ground.
Was able to test fit some rims on the arms as well. I tried R32 GTST rims (16x6.5ET40 with 5.3" backspace). As you can see, there is ample room for improvements... Limited by ~4" of "outspace"/poke on the rear of a 510 (i.e. 7JJ rim ET0), these arms and rolled fenders could clear a 16x9.5+35 rim. Whether that would clear the inner fender or not, I don't know but I doubt it.
I've been busy the last bit with a bunch of non 510 stuff (wreckering, squash, powdercoating, work etc) but I'm going back to the arms this afternoon. The bits for arm number 2 are all in the jig and ready for me to start coping.
Powdercoated cam sprockets for my buddy's Honda
Been working to modify the Z32 backing plates due to the rotated calipers. You can only see one caliper ear in the pic. This is pretty much as close to the Z32 orientation I could get given the design of the 510 semi trailing arms.
Went to a friends house this morn and got his KA running. Big shout out to Jeff for the help with remote troubleshooting!
Here's a video of it running. Some of the local yocals may recognize the car!

Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)