Had a look at Australian home stats, so quoting Home Av only Batting/Bowling
Openers
Warner 58
Hayden 57
Lawry 56
Khawaja 55,
I'd back Hayden/Lawry but Warner probably makes the squad
3-5 Middle Order
Bradman 98 (Locked at 3)
Labuschange 70 still some way to go but adds handy leg spin
Smith 64 (Locked at 4)
Clarke 62
Ponting 57
G Chappell 54/33
Bradman 3, Smith 4, leaving 5 open, on bouncing pitches Ponting's cross bat is very good, but Clarke adds some handy spin at times, I think the World XI aren't going to challenge us with spin except for maybe Sydney, Labu may have them both covered by the end of his career and his part time leggies are generally better than Clarke's spin anywhere but India.
6 All Rounder
Walters 57/31 On Home pitches he was an awesome bat
Miller 40/20
Comes down to if you want a batsman who can add decent part time, or a 5th ATG pace bowler who weakens your batting. Miller's home average is so good that a case for him at 8, if you'r playing 2 spinners could be made. (I'll get how to do that in the bowling section)
7 Gilchrist 45 locked at 7
So bowling just picking bowlers with significant wicket tallies, clearly the differences in bowlers av are much closer then batting averages, and impacted by the batting in their era's
Cummins, Miller 20
Davidson 21
McGrath, Bill Johnston, Lindwall 22
Lillee 23
Hogg, O'Reilly, Hazelwood, Gillespie, Thomson 24
Warne 26 after a whole stack of really awesome bowlers.
Questions often around Miller putting the overs in as a front line, but he did do it at times. So many ways you could slice this...
Cummins, McGrath probably locked in, and most would just pick Warne, and I personally have always valued Davidson for variety and batting at 8
Davidson, Cummins, Warne McGrath
However if you really wanted variety
Miller Johnston O'Reilly McGrath with Johnston starting with pace and swapping to spin to back O'Reilly, and strengthening batting with Walters at 6 and Miller at 8.
So being slightly controversial, because on Australian pitches this bowling attack will generate enough chances that you don't need a gun 5th bowler
Hayden 57
Lawry 56
Bradman 98
Smith 64
Ponting 57 (Since I think W XI will go pace heavy but Labu in the next 5 years probably takes the spot and at SCG Clarke plays)
Walters 57/31
Gilchrist 45
Davidson 25/21
Warne 17/26
Cummins 16/20
McGrath 7/22