That's exactly what I am suffering from right now. I know enough that if I screw up the measurements here it will ruin the handling and ability to properly align. Good idea to tack in some perfectly straight tubes to locate off of. That would probably be just enough for me to feel good about the measurements.
Thanks!!!
So if I recall industry standards was something like a 1/8” I am not okay with that much. But measurements of my car were way more out of square than that. It’s stock and never crashed.
The holes on your frame and great location point to start with.