you could buy a universal crossmember from summit or jegs and weld it in. put it in front of the old one, then cut out the old one. to advoid any shifting of the frame i would try to put the new one in before takeing out the old one.
casper- i too am looking for a c notch like the one he used. i just lowered 4/5 and i am hitting the bumpstops pretty frequent. i saw djm has one, little pricey but has everything and illusive fabrications has one also for like 65, not bumps or hardware, but illusives looks stronger. if i can get some 3/16 steel plate i might just make my own. let me know if you come across anything.
just found this notch. 65bucks. not bad