Roller Rocker Side Clearance

I am using Harland Sharp roller rockers on my 440. The instructions say to have a side clearance per cylinder from between .008 to .012. I recently took my engine apart to deal with other issues and am now reassembling things. I noticed some of the rockers and .047 spacers show interference wear on the sides. I called Harland Sharp and talked to the tech who said I could use their .031 spacers to make more room.

Having the minimum recommended clearance was obviously not enough. What are your experiences for the proper clearance? As I recall the OE rockers had quite a bit of clearance.