I just recently got the chambers in my grandfather's LC Smith lengthened by Mike Orlen. His turn-around time is measured in days, not months. His prices are so low they would make me question the quality of his work if he did not have an excellent and wide-spread reputation.
Check this out.
http://www.shotgunworld.com/bbs/viewtopic.php?t=36237 Granted, you would have to ship the barrels - but only the barrels, which do not have to be treated as a "firearm". Shipping them would be quicker and cheaper than driving to an adjoining state to deliver and pick up the barrels.