The only difference is, SK for small kit, does NOT have new springs and locks, K for Kit is the complete kit.
Honestly IMO, if your stock single springs are not worn out, you can run single OEM springs with that cam. I've ran .485 Lift 265 Duration cams on stock OEM worn springs and never floated valves at 6000 rpm.
Not sure if you're aware, the whole reason for dual springs if needed, is for more strength to control valve float and also if you get to much lift, you will get spring bind, so you use a double spring with less coils and don't have to worry about bind but have added strength for the valve float. You really don't need dual springs for that cam. It's not dual springs in the kit either, but if your current springs are in any kind of good shape, they'll work just fine.
What you can do, is install the small kit without the springs. See it how runs and performs. If you decided you need the new springs, then buy the new springs and install them. You don't have to pull the intake or cam just to replace springs. Using the right tools you can change springs without doing anything but removing the valve covers and rocker arms. So springs can be easily changed after the fact if you find they're needed.
