This sucks. Of coarse, Progressive tech support will tell you "these really aren't the correct application" but, running 13 1/2" shocks on your ironhead is one of the most common things to do to these bikes since the early 60's . . . Back then they just used panhead shocks. I think they just send these so you have to buy another set of springs (so search for a great deal on your 412s, preferably with 120/170 springs).
Too Weak (above)
This is what you want (or stiffer) 120/170
type wind at the top to hold the spring retainer. I think they look best with all that spring showing.
Get this thing down . . . a bit 'n da weeds
Low for Go Bro