And this from the hondatwins.net site;
"'68 - '70 had the fat cam
'71 - '73 had the thin cam
all parts are interchangeable between CB and CL for the same years (68 - 70, or 71 - 73)
you MUST use the cam and rockers for the correct years (either fat or thin cam)
the cam boxes can be used between the fat and thin cams but you will have to remove a little material to allow the cam to slide through.
all other parts are interchangeable"
"Nothing can stop us but fear and common sense”