Bolt in cage - minimum legal requirement for racing
Weld in cage - safety of occupant number one priority
You won't find data because none exists. Cages are fabricated custom based on what holds up in crashes. It's an art AND science, but more an art. A good cage builder will have seen hundreds of crashed cars, but likely never see any crash data other than g's on the car during impact.
If you want to be safe, get a proper custom built cage welded in with proper NASCAR bars, gussets, and foot protection. Anything short of that, I say, keep the air bags and millions of dollars worth of crash data on your side in the unfortunate event of serious collision.