Just use the green stuff, no need to try and get fancy, it's still an iron headed 460, right? Even aluminum heads would still use the green antifreeze.
I use Walmart antifreeze in my newly rebuilt 460 - same as always (and I'm cheap). I did get a new 3-row copper radiator from Summit Racing. I'm not a fan of aluminum radiators for this '75 Ranchero.
If a first start, try distilled water. Run it to check for leaks and flush out oil and assembly boogers. When you are happy with everything, drop the water and fill with green stuff.