I just installed some, they are a simple bolt in, just drop the ubolts & slip them between the perch & spring if you don't want to pull the whole axle. You do have to be careful about clearance between the tie rod & drag link no matter what you do :twocents. I used a set of Sky's steering arms since they are shorter than my Marlin arms. You could move your steering box forward but mine was already plated/reinforced where it is so the arms were way easier.
Also might want to put a small weld on the plates/perch to keep everything in place.