What is it about the chamber that is off? I have had barrels with questionable chambers or throats still shoot well. In an extreme case the once fired brass was over sized and out of round. With minimal sizing and indexing the cases it would shoot fairly well. I got rid of the barrel anyway. Make a chamber cast and measure carefully and spin on a concentricity gauge before going too much further.

Unless I know there is a problem I will only hand lap the lugs and have the action face squared when re-barreling for hunting rifles. The cost for a full "blue print" gets you pretty close to a custom action.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli