David.
I think its about 12 minutes, but I don't time it o its hard to say. When I mounted my G26 I didn't know you could take the aluminum plate off. So I felt mine was a bit heavier than everyone else's. So by using a smaller tank ( I'm lazy and didn't want to re mount the engine) I've made up the weight and more. As for the 2-56 hardware, is your stuff fully threaded rod or pushrods with threaded ends? Sorry for asking a dumb Q, I'm just not familiar with that setup.