Bill,
You left out one key word "EXACT". That's the word that makes me unsure. I hope you can see it from my point of view. It doesn't say "ANY ignition or ANY clutch disc and pressure plate. It says Exact Equivlent.
Pistons for my 30 year old car are in short supply. I'd welcome a new source for pistons. I feel there are advantages to using forged 2618-T61 aluminum pistons.
The ITCS states:
"Equivlent pistons shall provide the same dome/dish/valve relief configuration, ring thickness and spacing, pin height relationship, weight and compression ratio as factory replacement oversize pistons"
Your interpretation is that as long as it meets the above statement it's ok if it's different in other ways. such as stainless grade, full floating pin, taper, skirt style and size etc. etc.
It sure leaves a lot of room for some improvments over a factory standard cast piston. Just decreasing the size/area of skirt and the design features to the skirt can make improvements in friction. Other improvements such as stainless grade, full floating pin, taper, etc. etc.
It's late got to go,
Harry