[vettestr]

I think most of these bars are for form more than function to use your word options. The best protection is a true 5 point cage. This is above and forward of helmet with side or forward bars to protect the driver.
The original bars although the standard of the day when mounted on todays car are often just for looks. The bar must be taller than the drivers helmet (less than 3 inches but not allow helmet to hit bar anywhere). Draw a line between roll bar top and front frame crossbars to determine envelope of protection. Where would everything collapse (body torn away) to steel structure and then would driver be protected inside this zone and the windshield frame is not a support structure.