Where can I find more information on that?
Mark A and georg both have an adaptor plate to mount a 4 bolt master to the 3 bolt firewall. fairly simple, need to make another line to tie into the rear brake on the passenger side frame rail.
It would be an upgrade of the master cylinder from one w/ single outlet to the dual output master. Not sure what year they changed them.
Does yours have power breaks? I think I remember seeing a '69 with a remote booster?
The switch over happened in mid 1970, I have an early 70 with single circuit and had a later 70 that had dual circuit.