For the bent I-beams you will need longer springs, so stockers will be a no-go either way. Lift coils however are made in a number of stiffnesses, raging from fairly soft for offroad flexing to really freakin stiff, I had some 4" lift beasts on my '78 F150 (powered by a one fat pig of a big-block) and I didn't even need swaybars at freeway speeds, I could pull a 3-lane change at 75 mph and truck only slightly leaned, even the brand new SkyJacker shocks couldn't keep up with these springs. So I guess you'd be looking for some very stiff lift springs, I tried looking up on partsamerica.com what my F350 uses but there is no data for the springs (which is really odd), so can't recommend any particular rate... If I do find something I will let you know for sure tho.