I've used Progressive 412 (13 inch) on my Tourer and Progressive 440 (13 inch) with the HD springs on my Interstate.
The 412's did fine on the compress but rebound damping wasn't great. The 440's were just not enough, even with full pre-load, on my Interstate when fully loaded and 2-up. She always seemed to be squatting a bit in the rear.
Moved the 440's to my Tourer and they are great there.
Ordered a set of Works shocks from Dave @
http://www.xf6-custom.com/ (he has other bits for Valkyries too, check him out, nice guy) and have been very pleased with them. Works shocks are custom built to spec for you. They spring the shocks based on the weight you are expecting to carry on your bike.
They are quality made here in the USA and when I took'em out of the box I could tell right away these were great shocks. They were perfect right out of the box, no added preload. It raised the rear of my bike back level it never squats when fully loaded. I've had others riding behind me comment on how everybody else's bike behaves on the road versus mine, how more stable mine is.
They are pricey no doubt but you get what you pay for in this case.
Don't remember if I have the Billet Trackers or the Street Trackers but Dave can help you figure out what is best for your application.
http://www.worksperformance.com/html/street.htmlMy shocks have the chrome springs and appearance cups on both ends.