Dylan, part of the problem with the beam that came with No. 9 from the Ramsdell's farm appears that it prevents the diagonal stays from the smokebox to the beam to be in the proper position. I seem to remember trying to figure out the proper geometry when marking drill hole locations in the smokebox last year.
I believe Jason told me the existing beam sticks out from under the pilot deck plate and that it should be flush with the front of the plate for protection of the wood. If Brendan and Dean had not donated a new beam, we would have cut the existing one down to the proper size this coming weekend.