Info regarding equipment adoption for Matt P. as per chat
Bench shirt approval:
IPF:
"The next year in 1992, the World Championships came back to Great Britain, the venue being the newly opened National Indoor Arena in Birmingham.
It was at these Championships that the Bench Press shirt was approved by Congress."
https://www.powerlifting.sport/federation/history.html
Someone like Mason Jardine may know when they were first approved for APF/WPC, I suspect as soon as John Inzer made them.
Bench shirt invention:
https://musclemagfitness.com/everything-you-wanted-to-know-about-bench-shirts puts John Inzer's development and first marketing of bench shirts at 1983. Todd, Pollack et al put it at 1973 but I think that's a typo.