It seems they are ready to battle the new Ford 429 engine!
Compression: 14.9
Lift: 0.676"
Throttle Bore: 4 @ 2.250” 4B-4500 (Dominator size)
Valves: 2280(I)/1620(E)
Dual Coil Springs
Heads: 12 Degree LSX/LS7
https://sdparts.com/details/gm-perfo...parts/19201806