Air bags can and do get put in a alot of different set ups, including leaf spring set ups. Or how about some dropped Spindles on the front. If you can't get past the bump stops move them in to higher position and notch the frame so the axle has more clearance. Notching the frame takes alot of work and knowledge and best left for show cars or something with a full chassis like a mini truck, hot rod or early custom. Or if you really want to go old school just cut the body from the floor pan and channel it over the pan a few inches.
My point is to make a car sit lower than what it would sitting on the bump stops takes cash or $hit hot bodywork knowledge.