I have a couple of 427 medium riser 2x4 intakes,one is supposedly milled.Is there an obvious way to tell which one and how much.I don't have an assembled FE motor to set them on either although I do have a bare block and heads.
Most times, the ends that seal against the block are milled seperately and not a cut from one end ot the other otherwise you would screw up the manifold in the middle. This usually leaves a low spot on each end verses the middle of the manifold. Also, look for lond sweeping arcs left by most machine shops since most can't afford to buy the small cutters like the factory or manifold makers use to mill the ends with.
Correct me if I'm wrong, but since you mill an intake to sit lower, if you measured the distance between the flanges that bolt to the heads on the bottom, wouldn't there be a difference, or perhaps from a bolt hole to the top of a flange? Maybe they are all cast different but it might work.