proportioning/metering/distribution valve clarification

The 69-74 part will work with your combo, if you can source one that doesn't leak (there was a bad batch out there). I did the 9" drum to K-H disk swap on my 67 Barracuda, so I can vouch for that.

Leak? an external leak in the switch seals of fitting connections... or are you speaking of leaking past the PSI set point of the PV?