Won't damage the turbo if the restoration is done if the engine is R&R'd. Turbo will come off with the exhaust manifold. If turbo removed separately, do a thorough inspection, and keep the ends sealed or covered to prevent the introduction of particulates. Shouldn't damage the turbo if proper procedures are followed. The only way this process could hurt the turbo is if some particulate or something got blown through the exhaust to the impeller side of the turbocharger. Not likely to happen if normal standards of cleanliness are maintained.