The Following item has not been proven to have been used in period.
The use of roller rockers is a reletively recent development.
It was widely used as a replacement for the cam followers on Ford Pinto engines.
This was seen as a cure to the short life of the original camshaft and followers.
It has since become a must have for other engines especially as high lift rocker assemblies.
The following is a picture of a roller rocker as fitted to a Mini A series engine.
The principle of operation is the same for other engine applications.