I'm looking into the possibility of running 1.6 rockers* on my -461 heads. Will the stock, as-cast pushrod holes in the heads likely need to be elongated to allow clearance for the slightly changed angle of the pushrods?

*(I'd prefer to run full rollers, but since they must fit under OE stamped steel valve covers I'll probably have to compromise with Comp Magnum roller-tip rockers, which I'm quite sure will clear the valve covers.)