What is the deal with the backing plates for these bars being drilled off location? Seems everyone so far has found the same thing. Apparently they have one guy drill the roll bar plate with a drill press then a day later they have someone else drill the backing plate with a hand drill with their eyes closed. I had a couple holes 1/4" off. Seems odd for a reputable source.
I've heard that from a few people. I guess I was just lucky - everything lined right up.
Now, I did notice one thing that might help others. When we attached the transmission tunnel backing plates, I mistakenly drilled all of the holes for both sides (by drilling through the holes in the bar feet) at once. When we tightened down the first side, it pulled the bar down a little more, which caused the freshly-drilled holes on the other side to be off by a small amount. It was easy to fix - I just re-drilled, effectively making the holes a little larger - but the problem could've been avoided by drilling and bolting one side before drilling the other side. I also sprayed some paint around the drilled holes to (hopefully) inhibit rust.
For my plates, I noticed that the hole spacing was not identical between sides, but they did match the bar. (That is, each plate matched a specific side / foot of the bar but were not interchangeable between sides.)
The only manufacturing issue I had was the tab on the driver's side tunnel foot that interfered with the ~1/2" raised section around the e-brake assembly. (I posted a picture of that earlier in the thread.) A cutoff wheel made short work of that.
If you need to make another plate due to holes not lining up, and don't have a welder, the nuts could be attached with epoxy or JB weld or, if you're careful, even hot glue. They're just on there to address the limited space in the tunnel due to the torque arm.
I'd love to see what you do with the harness bar.
Just out of curiosity, how tall are you? I'm 5'9, longer in legs than torso, and I'm having trouble imagining a bar configuration that would allow sufficient seat travel. Of course, if I was really serious, I could have just ditched the big back plastic panel and freed up all kinds of room. If one were creative, that would also let the bar sit another few inches back, nearly flush against the bulkhead. It should be possible to modify the rear panel to allow that, also, but I'm not the greatest at calculating intersections of angled cylinders with curved surfaces, so I just skipped that.
I could've bought a Miata.
Everything is cheaper from tires and brakes to roll bars and engine swaps, and everything has been done a thousand times and documented.