It sounds to me as if the Great Plains was not "the One" in your mind anyway. If the bow/riser were the perfect fit, I'd go with the new limbs. Well, I'd probably also buy a used bow to use until the limbs were ready. If this bow was the perfect fit for you, you wouldn't be making this post though, so maybe selling the riser and going with a whole new set-up would be the best for you.
I know if my Kanati were to break, I'd be in tears. I truly hope it outlives me, because we are a perfect fit.
On the other hand, I like the riser of my Orion, and did have a set of recurve limbs made for it. If it were to break, though, I'd probably wait for Jason to build me one of his three piece bows (something that is nearing production).