I don't have any experience with the 51XX bilsteins on a LC but I can relate a little experience with putting bilsteins on the front of my 71 Bronco which has a nearly identical coil sprung front end. I originally went with a set of 255/70 5150's and the front and was very underdamped. After looking into messing around with them, I eventually got a set of 7100's that can be revalved by any old COMPETENT offroad race shop. The 7100's started out with 255/70 valve stacks and after 3 revalvings finally got them to 330/110 where they work really well. Keeping in mind that a 71 bronco probably weighs about 1/2 - 2/3 what the typical cruiser weighs, you may have to go well beyond 320/110 to get your front and where you want it. Here in SoCal we have many good Baja Race truck speed shops that can revalve shocks very cheaply. If you don't have the same access, you may want to call Bilstein and tell them that you want to send your 5150's in to have them revalved to whatever the valving is on the stock replacement bilsteins.