A set of higher ratio rockers will work well here. The .557 is .631 with a 1.7 rocker if you can find them. Almost roller performance with a flat tappet cam. Sig Erson made a high ratio cast steel rocker years ago in 1.75 advertised. I used it with a .590 cam and L88 chev valve springs. I was shifting below 6000 rpm. Worked great!