$50 for a manifold is not that bad. It will cost almost that much to have one shipped to you. 1 or 2 barrel doesn't matter for what you want, they are the same but I have heard the 2 barrel has a larger outlet. Don't know how true that is. Don't know if I would take the flapper out since you may have too much exhaust hitting the bottom of the intake without it. The flapper is not as much of a restriction as you would think if it is working. The restriction (tater) is upstream from there where the manifold makes the bend to come away from the engine into the outlet. That 90 degree bend necks down to a space barely larger than one exhaust port, at least it did in the 3 I cut up. If you can get one locally that has a working heat riser and the intake to exhaust bolts are not broken off, go for it. You will be money ahead in the long run.