Rockers 1.5 ratio or 1.6???????

.573 divided by 1.5 equals .382, this is your lobe lift. .382 x 1.6 equals .6112, that would be your lift with a 1.6 rocker. That's too close in my experience. The only real way to know for sure is to know your EXACT installed spring height, put the spring in a vise or a spring testing tool, compress the spring to the installed height plus .6112 minus your lash and measure for coil bind clearance suggested by the spring manufacturer. Don't forget to check for retainer to seal/guide clearance too.