Harry
You may be able to get away with not castrating Kune
litter brothers ( as long as there are no females about to wind the hormones up
) BUT remember that Kune Boars mature sexually at about 5 months, you may have to seperate them - adjacent paddocks, so they can still see each other, for welfare considerations.
Bearing in mind that late castrations will cost more (heavier = needing more costly anaesthetic) it's not worth doing you doing it post-weaning for meat pigs, unless it's for health problems.
IMPE I've had more meat from a castrate than from an entire of similar age (14-months 82kg of cuts vs 13-months 54kg), though at 7-months the entires had less fat on the carcass than the castrates.
See how yours get on - they could be ready for the great abbatoir in the sky before 11-months (especially if they start getting "Boarish" with you
)