It would be interesting to dyno a 273 with the HP manifold vs the LD4B. (and start the readings out at 1000 rpm instead of 3000 like most dyno operators do)
As you're going for consistency this is nearly impossibly to do. As soon as you WOT it, it is going where the converter flashes anyway. Doing it twice for a back to back comparison consistently would be unlikely. How long are you at WOT under 3500 RPM anyway?
I've got a Mustang dyno and I can do part throttle dyno pulls as well as WOT, which would be useful for really comparing the intakes. I've even got a 318 powered plymouth, but it currently has a Holley Street Dominator on it.
I am very curious to know if the LD4B is really better than the Performer, and I want to know if the LD4B is the same thing as the Weiand Action Plus, but I'm not spending $750 on intakes to find out. haha.