The F shock should be about 14.25 inches. The Custom had 13 inch shocks.
They are eye to clevis with the eye up top. Really, if you get about 13.5 - 14.25, you should be good.
I would recommend either Hagon shocks through dave quinn or progressive shocks.
They are about the same price either way I think, about 200 or so.
The ride IS the adventure. The destination is just to get gas!