I do not know what other stock you can choose from. I hated the stocks on the AR-50. They are too long seriously who does Armalite make them for? I do have a AR-30 and had the stock cut down several inches. I was showing it to the person who bought my AR-50 and he promptly cut off the butt plate and then removed the metal he needed for proper length of pull. He machined it nice then screwed it back together. He also modified the cheek rest somewhat.
That might be an option for you instead of buying a new stock.