It definitely depends on size. I would not go past 290mm for the King2. Any longer and you can 1) have a slower than desired headspeed, and (more seriously) 2) run the risk of the main blade striking the tail blade. Other than that, any symetrical blade should be fine. Depending on the brand, you may need 1) small washers/spacers if the blade is thinner than the King2 blade grips, 2) if the area of the blade inside the grip pivot point (can't remember what that area is called) is longer than stock, it may rub against the inside of the blade grip, and you'll need to remove excess blade.