You've misread the recommendations and diagrams; there is no using the '70-up voltage regulator with a '69-down alternator (unless you do some ugly hacks to the grounded brush on the '69-down alternator). You need a '70-up "dual-field" alternator (one with two 1/4" spade field terminals, each attached to a brush that is completely isolated from ground) -- either a '70-'71 roundback or a '72-up squareback.
(If you are determined to keep the alternator you have, then an appropriate regulator, not the '70-up type, is called for. I like the Standard Ignition № VR-128 best.)