Saying that Greenidge and Haynes/Hunte outclass any two of Hayden, Simpson and Trumper is arguing over the finest of margins. Marshall and Ambrose might work over Hayden, but equally, McGrath and Lillee would probably work over Greenidge.
I would feel safer with Bradman coming in after the loss of an opener than literally any other batsman in history, regardless of whether its 1/2 or 1/200 (actually in this case I'd back Bradman more in the former rather than the latter).
With Smith at 4, you literally have the best uphill skier in living memory. Always played memorable knocks against the better bowling attacks in favourable bowling conditions.
I seriously think real selectors would pick Gibbs over Holding as the 4th WIndies bowler in most conditions to avoid Sobers having to shoulder the entire spin load (assuming modern playing conditions).
England have a better claim to openers who are a class above Australia's openers but literally no side could ever claim a better middle order than Bradman, Smith, Waugh and Border (or maybe even G Chapell at 5 instead of Waugh, but that's hair splitting tbh)).
The best argument for Miller in the Aus ATXI is that Bradman covers his weaker batting and he's a 5th genuine bowler who let's you pick O'Reilly to bowl alongside Warne (even though we never really saw MacGill bowl alongside Warne even when he was clearly the second best bowler available (like in the 05 ashes when McGrath was injured).
The Aussie all time squad would have the flexibility to play two spinners if necessary, but the starting XI is going to maximise batting output in the top 7 because McGrath, Lillee, Warne and Davidson/Lindwall/Cummins is ridiculously broken strong as a bowling attack.