My rudimentary understanding of the reaction between different metals is that unless the metals are touching there is nothing to worry about - so that's kind of my starting point. Would a waterless fluid be worse with the different metals than a water & antifreeze mix? I suppose it is possible. I am definitely not an expert on this.
I've got a new radiator and plan on getting a new heater core (I'm by-passing it for now). Engine is original...but what pump are you referring to? Please let me know - I may look into replacing it.
My general mantra is to avoid water. The car has made it this far....I want to make sure it keeps going. I also happen to be into non-ethanol gasoline because it is said that ethanol absorbs more water. (Ethanol also didn't exist in '69 so It is also partly staying truer to the times).
Here is a link about Ethanol fuel:
http://www.mossmotors.com/SiteGraphics/Pages/ethanol.html
Here is a link to finding non-ethanol (and usually higher octane fuel)
http://www.pure-gas.org
Here is the link for the coolant:
http://www.evanscooling.com/
Here are 2 videos about the coolant:
https://www.youtube.com/watch?v=t7PykrgzWPQ
https://www.youtube.com/watch?v=KRLXKW2ph0w
Yeah, its Jay Leno, but from what I've seen he really takes restoration and non-restoration seriously.
Hope you find this informative. I'm an admitted novice so I gladly offer my comments with a grain of salt.
Very best,
Jason