The much anticipated High Tower Armory 90/22 bullpup stock conversion kits are now available, and so far the reviews from customers seem to be pretty good. Check them out over at HighTowerArmory.com.
Just a note, these bad boys are selling like hot cakes so their site may say out of stock, keep checking back or sign-up to be notified when they come back in. They are actually available, I swear!