RHS Heads .. Not happy.

I've run no less than 10 sets of PRW STAINLESS rockers on our RHS heads with NO problems. They sit towards the ex. side of the stem, but they will be fine that way. The SWEEP is what's important and that it's close to the middle. There are a bunch of head combos out there (ford, chevy, etc...) that end up the same way for various reasons...most of the time because of valve length differences over stock.
You need to remember the stock stem is 3/8 and the RHS is 5/16 so even though it doesn't sit smack dab in the middle it'll be OK.
Do you have the stainless rockers or aluminum?