First, check your chamber with a Pin Gage, not calipers. For I.D. measurements calipers can be wildly inaccurate because they are severely influenced by an cocking or off center positioning. Pin gages only cost about 3 dollars each and it's a no doubt means of checking a bore.

Second, once you know the exact size you need yoiu will want to contact a Chrome Plater that does Hard Chrome Plating. Many times I've had swaging tools Hard Chromed to tweak a size by up to about 0.005 inch on diameter.

The reason why you want to go with Hard Chrome is because a "bushing" with a wall thickness of only 0.002 inch is not possible because this amount of thickness just doesn't have sufficient strength to withstand the force applied by a reamer, what will happen is it will "peel" and just wad up around the reamer. The only way to bush this chamber is to start with an overbore that will provide at least 0.05 inch of wall thickness for the bushing. With all the work involved it installing a bushing it will be much easier and cheaper to simply have the chamber hard chromed. BTW, areas where you do NOT want plating can be masked off with a special "paint" so it is possible to ONLY plate the chamber.