22LR - something like a Cooper or really good Anschutz
6.5x47 Lapua - custom rifle with BAT 3-lug action, jewell trigger, krieger barrel and McMillan stock
8x68S - Win/Mauser custom controlled round feed action
.375 H&H or 9.3x62 - Win/Mauser custom controlled round feed action
.500NE DR - WR, H&H or classic Rigby
or .458 Lott - Heym Express action (nice and heavy to shoot 550gr at NE speeds)
or .425 Express - Win/Mauser custom controlled round feed action (to shoot 450gr at NE speeds)

Having said that, I'm not sure I could live without a .303 and 9.3x74 falling block though (really really really want a Hagn take down set with those barrels)

... or a .450/.400 NE....

... or a 12 bore....

Am I alowed 6/7 plus a shotty?

If you get a rifle with multiple barrels, does that count?!

Oh - and I forgot a muzzleloader.........