will stock rockers work with larger springs?

Rustyratrod.. the only reason im using the tall installed height is bc the head were set up for large double springs for the larger solid cam first. I cant make that any smaller now. I used a old head I had and mocked it up. Seems like the rockers will wipe on the stem fine. I think if I shim the shafts it will help a lot. How much can you shim them safely?