engine noise

Depending on the type of valve springs you are using - 273 rockers can sometimes touch the side of the spring retainer on the underside of the rocker arm. I have a set I use on my car and I found that I needed to re-leave about half of them on that part of the arm. The old DC mopar hot rod books talk about doing this. You need at least .040" clearance if my memory serves me correctly. This could be another source of your noise -