I sent my ductile rockers to RAS (now RAU) and had bushings installed. They'll blue-print the ratio for a few bucks more. It included undersize banana grooved thick shafts and hold-downs. I have another set with some light galling that will be sent in to be bushed, or I'll get their stainless roller tip set for about $1k.
DVORAK Machine offers a do-it-yourself kit.
http://www.dvorakmachine.com/rockerarms.shtml