One thing I can tell you - once you settle on what you want to do, is be sure that if it is a re-built turbo the shop that did the work also carefully stoned (preferably) or filed all the "wire edges" off the impeller blades, or you will have to put up with a very annoying "turbo whine" that won't go away until next r&r.
Have you checked with an aviation accessory shop that may have an aircraft-application bearing set that may work as a direct replacement?