Stefan,
Please note that the sanctioning bodies (NHRA, IHRA and AHRA) kept a tight reign on the S/S car rules and still do today It wasn't until the mid 70's that the rules were relaxed so it's a sure bet the suspensions were "improved" shortly after the rules changes and continued as the ET's dropped. I'm sure if a racer was "creative" he wasn't going to advertise. The AH cars of today run on the ragged edge of poor handling as seen by the number of on-track incidents in 2015.
The LO / BO cars were delivered to Hurst with cheap OEM shocks. Hurst installed the longer heavy duty shocks . I do not know what brand they were but there weren't many shock makers at the time to choose.
Roll bars and frame connectors were added by the new owners to meet tech (safety) requirements. I'm not sure when torque boxes were first put into play.
As far as the record on a stock suspension I don't think anyone noted the record or cared to at the time. The LO and BO cars were delivered from Hurst with SS spring and HD shocks so technically they weren't "stock" to begin with.
For what it's worth: I had a 10.50 car on 3000 lb SS springs, HD Drag shocks, 3 inch inboard spring relocation, and a mini tub. I decided to move up an index to 10.0 and it was a handful on the launch. I also broke the 8 3/4. I found 10.0 secs. to be my limit, and quickly changed to a 4 link, coil-overs, and a DANA 60. The changes made the car fun to drive again and more consistent.
I hope this helps.
:glasses7:
