I am running 5 leaf 2.5" lift springs (don't remember the brand) on the front of my CJ7. I built a bumper that is sturdier than Bullet Proof's stuff and that along with myself(a rough estimate of what a winch would weigh) I have little to no sag. My bumper probably weighs in at about 80 or so pounds. I weigh about 155-160. So with about 230 pounds on the front I don't sag.
My roommate however, purchased a Reunel front bumper and a Warn XD9000 winch(about 400 pounds total). He was running a Pro-Comp 4" lift with an extra leaf and it was still sagging almost a full inch. We just got finished pulling the springs and having 2 more leafs added to the stack. There are now 8 leafs in this thing. It looks like something off of a Peterbuilt. It is rediculous. But that is what it took to get the nose up.
Anyway, you have my rantings. Hope they didn't annoy you. I would probably try to get a friend or 2 to stand on the front bumper and see how bad it will sag. Then go from there. Hope this helps.
'85 CJ7 258 w/Weber Carb and Nutter Bypass. Dana 44's F&R, 3.73 gears with Trac-Loc rear. Always looking for peoples $0.02.