Well, I am meticulous about these things in general, but the problem is the scene around here is far more centered on NHRA when it comes to builders. The only reasonably-priced builders all work on drag cars in high volumes. They do know how to build safe cages to professional specs, just not NASA/SCCA specs necessarily. I found a couple shops within range that know about NASA/SCCA rules, but they're asking for ~4x the price for the same pipes, same welding, same specs, etc. So if I did (or when I do) put in a cage, it will likely be me carrying a copy of the relevant rules down to a very reputable NHRA-based shop here to have them do the work. One in particular that I've been looking at, about 2 hours away, is also well-versed in doing LeMons cars, so that should carry over some as well.
But in any case, I've dropped the idea of putting in a 4-point for now. Going to wait until a full cage makes sense. See this thread:
Rollbar / seats / harness stuff, yet again....
Also, Spohn, when I've been looking over cage specs myself, I'm concerned about your 1.75x.095 build. Seems like for NASA (if you plan to do NASA TT stuff), 1.75x.095 is only allowed if you can get the car under 3000 lbs comp weight, otherwise you'll need 1.75x.120. Or did you have some plan to get under 3K somehow?
Edit: it could also be, of course, that I don't fully understand the build rules. Maybe you can step down a size when you've got more than the required minimum tubing (e.g. extra rear cross-bracing like you've already got). Still, I'd look into it on my own if I were you.