That sounds strange to me. People use various different rockers with whose ever aftermarket heads so the head people have to stay with the stock geometry on the rockers or they would have to have somebody make a specific rocker for their head. Pushrods are easy enough to get in different lengths so thats a different situation. Too tall pushrods will push the rocker tips toward the outward edges somewhat like that. Are you absolutely sure you have the correct rockers?