Here's a few pictures illustrating the conversion to BB Chevy roller rocker arms.  This is intended to be used on rocker-shaft type cylinder heads - it won't work on the newer small port heads.  The rocker arms I used were Harland Sharp 1.7:1 rollers, the studs were ARP, the guideplates Competition Cams, and the pushrods were case hardened Big Block Olds pieces.  The entire assembly fits within the stock valve cover with no clearance problems.

The real trick of the installation is the adapter plate.  Detailed drawings of the adapter plate can be found on the next page.  The plate bolts to the head with six hex capscrews which penetrate into the water jacket and therefore require sealant upon installation.

The head was set up at a 10 degree angle on the bed of a vertical mill and the rocker shaft pedestals were removed, creating a flat area where the adapter could be installed. 

The Competition Cams Oldsmobile guideplates were used after enlargement of the rocker stud holes to allow the use of 7/16" ARP Big Block Chevy studs.  The plates are very hard, but this is an easy task for a well equipped machine shop.  The studs and guideplates are installed on the adapted plate and torqued to ARP specs.

Here's a few more shots showing the arrangement of the adapter plate and fasteners.