I believe that Jake is referring to the small chain tensioning paddles that guide the cam to cam chains on the five chain early motors (the brown shoe like device just to the right of the extension shaft in the picture, under the cam to cam chain).
This is not difficult, but does require quite a bit of work as they are under the cam covers and requires locking the cams down while swapping them out. Expect this type of work to go well north of $1,000.