Deck height is identical. Valve lift too. Same preferred springs, same pushrods, same lifters, same PORT spacing (critical). I don't know if the exhaust studs are in the same location.
Look at a GN motor. You'll see the same odd valve stagger as the S1. That'* the giveaway.
When I selected my 105 springs last winter, I found out two weeks later that the GN guys go to the same exact spring. And it'* not pure coinciedence. The 95 and newer L36 and S2 L67 are too much changed. But the S1 is truly a direct descendant. Even the spring install height is exactly the same.
1.72" on the nose.
Interesting, eh? I've been keeping it a secret all this time because there'* so much benefit to it and I don't want anyone getting a leg up on me.
And on the serious side, there'* actually zero benefit to it at all. Automotive technology improves every year. But you can't put GN power on a 4T60E or 4T65E trans without a serious investment, so it'* all of no consequence or advantage, really.