Couple things to think about,
The uni has a taller mast then the sloop. Make sure you get the proper length cables.
The sloop has the cable that runs across the tramp that the jib blocks connect to. I dont remember if the Uni has the tracks rivoted onto the hulls to accomodate this?
I put a spin on my 5.5 sloop when I had it. I had a bunch of pictures on how to do this, Ill see if I can find them. However, from past experience, I would REALLY recommend switching boats to a F16 or an F18 before I put a spin on a 5.5.