sbc rockers rubbing on springs.
The best information I can give is to refer you to Jim Miller Engineering or "Mid-Lift" geometry. The tech pages explains in detail the relationship of rocker arm geometry and push rod angle. Before you spend anymore money or grind your rockers, visit this sight. It seems to me that the rocker is to far down on the stud reducing your clearance. The person who suggested push rod lenght, is on the right track. The springs not fitting tight in the retainers could also be a contributing factor. The sight also addresses the problem of locating the rocker properly on the valve. This is a common problem with stud mounted rockers and guide plates. As was also posted, offset rockers and modified guide plates were used to correct this problem and indirectly solved the spring clearance problem.