That's a valid question. I did say 228 route but I would be open to any group 1 (228, 248, 270, 302). I had seen somewhere that the 248 was more difficult to tune due to siamese cylinders but truthfully I don't know if any of the others would be the same. I know i haven't seen hardly any of these on Facebook marketplace let alone close to me in NW Arkansas. Id prefer not to get one that needs a bunch of machine work.