No reason why not. You will need a reamer with the appropriate bushing diameter and a relatively long throat. You have to decide if this rifle will be capable of shooting both .303 and .303-308 or only .303-308. Because your bullet is now .003 smaller, the neck will be equally smaller, and may or may not fire .303-308 as well if you use a standard .303 British chamber and throat. Designing a .303-308 reamer that makes the approprite clearances in the chamber may preclude the use of factory .303 British without first turning the necks. Hopefully that helps you a little.