8 x Pawns: 3317
2 x Knights: 5338 "Special Leap"
2 x Bishops: 6337 Dodge
2 x Rooks: 7339 Block
1 x Queen: 9349 Block, Dodge
1 x King: 4338 "Special Leader"
Apothecary: None
Team Re-rolls: None (see "Special Leader").
"Special Leader": If the King is on the pitch and standing at the beginning of the Chess team's turn, then the King may use the Leader skill that turn. If the King is not on the pitch, or does not start the turn standing, he may not use the skill. The skill may be used each turn, provided that the conditions are met.
"Special Leap": The Knight may use the Leap skill as in the normal rules, except that the leap automatically succeeds (do not roll a die).
Curiously, the cost of the team works out at about 1,000,000. For example:
8 x Pawns @ 20,000 = 160,000
2 x Knights @ 60,000 = 120,000
2 x Bishops @ 60,000 = 120,000
2 x Rooks @ 100,000 = 200,000
1 x Queen @ 180,000 = 180,000
1 x King @ invaluable = NIL
Notional cost of King's "Special Leader" (say 4 uses per half x 50,000) = 200,000
1 x Fan Factor (say) = 10,000
Total cost of team = 990,000.
By some fluke, the cost of the players, as well as appearing to be in line with "normal" BB player costs, turns out to be in proportion to the standard notional value of chess pieces.
I'm not sure the side should be allowed Skill Advances, since they could become quite beardy. But depriving them of an Apothecary might (just) balance this out.
Oh, and by the way, you can test the side right away just by using the pieces from any chess set. It's fun watching the King lurk deep in his own half, desperately trying to avoid the opposing players

Hope you like it.
Cheers