Well I dug out the drawing for my ATI damper, and found a number of interesting things.
#1.) ATI are most certainly using the CAD from the consultation I did with them in 2008. I specified 340hp N/A...which I don't think many here would have to balls to pursue. So that's where that # came from.
#2.) My drawing is SK183K, meaning someone else has had an SK183K2 done. (I think I know who that is)
#3.) My 6-rib accessory drive is 6.78" in diameter, not the 6" I've been mis-quoting. The OEM one is 5.52" for comparison.
#4.) The steel hub that is pressed onto the crankshaft is significantly different for my damper. You wouldn't be able to interchange 5 rib pulley wheels ect. The hub to crank measurements are exactly the same. (15 thou interference fit)