Yeah, putting it off until the 80's probably means there's less budget available for it. NASA might only be able to manage it as an experimental development program. DoD would have moved on to other expendable launch capabilities, and the Reagan Administration seems less likely to have been willing to fund an ambitious clean-sheet program like Shuttle turned out to be. Assuming NASA is just operating some retread or modest evolution of Saturn Apollo hardware (like your ETS timeline) then the Gipper would be a hard sell on that. I always thought even your Saturn Heavy would have been a push (though I thinkyou were right that Soviet heavy lift developments were the only real way to put a thumb on the scale). If by some miracle it happened, I suspect the only real advances over OTL would be in avionics, and they'd be rather modest.