I ended up with the Wilson Combat Spring Kit #178. I will install it when S&W returns the revolver after the "M" mod and checking the cylinder sticking issue.

BTW, just got in a Lyman trigger pull gauge and will be checking when it comes back. My little 2in Kimber DA-only K6S came in with an average of ~6.75lb trigger and that feels great! I'll also check my old 642 in the next day or so, and then add the Apex springs I ordered for that as well.

Things are looking up...