2to 21/4 pipe should do it with good mufflers.as for the high volume pump i would buy a melling replacement pump it will pump more oil than the stocker but wont suck the pan dry or flood the valve covers with oil(small blocks are famous for that)we used to stuff pipe cleaners in the push rods to stop over oiling in the valve covers.or you could install restrictors while you have it apart they go into the oil holes under the main bearings.
