You might check with Charlie Melk at Charlie's Brass Works (
link) - he mentioned to me the other day that he has spot-plating capability at his shop (I was asking him about what happens when he has to move and remount the receiver to increase the gap on an already-plated horn). Give him a call and I am sure that he could tell you what would be involved in mounting a leadpipe and what the cosmetic results would be. You can purchase leadpipes that
are already silver-plated, and then it would probably just be a matter of spot-plating at the solder-joints?
At any rate, he's very nice to talk to and will give you the straight scoop...
I know that Charlie sells his own leadpipes in both raw brass and silver plate - he replaced the leadpipe on my old Bach with one of his and the change was incredible.