I'd be OK with SMarsh going as the extra batsman. He can play spin and his form up until getting injured was pretty good.
Handscomb becomes just the second Strayan to make 50+ in each of his first four Tests. I've never heard of the other, one Herbie Collins.....
Australia had a lot of outstanding cricketers before and after WWI, Trumper and Macartney were two of them. The "Big Ship", Warwick Armstrong, was the captain of a magnificent team, some say the first golden age of Australian cricket.
There's an apocryphal tale about Macartney who was nicknamed the Governor General: the real Governor General was being driven around near the SCG one day when he enquired of his driver why there were such large crowds about. The driver, a Sydney local replied' "they're going to see the Governor General" bat. The real GG was somewhat bemused and instructed his driver to leave him at the ground so he could see who this "Governor General" was.
Ask Lee, he'll tell you all about them.
Ability to play spin should be just as important as experience in the conditions. We know what to expect and having guys with proven success in India could make a big difference. I'd be far more comfortable with Lynn or Maxwell than I would with Agar or Head.
Batsmen: Renshaw, Warner, Khawaja, Smith, Handscomb, Maxwell/Lynn, Cartwright
Bowlers: Starc, Hazlewood, Bird, SOK, Holland/Lyon
Keeper: Nevill/Wade
Lynn's had a shocking time in India though?
Comparing the two, SMarsh has 2213 career runs at 40.98 in the IPL, while Lynn has only 89 at 22.25 (or at least that's what I can tell from the IPL sites).
I suspect that they'll take Agar before either Maxwell or Lynn as he can bat and provides a spin option. I think that they'll also retain Lyon ahead of Holland. The rest of the squad you suggest I agree with 100%.
I'd rule a permanent line through Maxwell as he strikes me as a narcissistic egotist who puts himself before the team.