...bend it into a sharp "U" on the end, then stick it down in the port and scribe a line against the intake flange.
As far as "performance shops not milling intakes anymore", I would have to disagree with that. It's still common practice, and a few intakes (such as on a Ford FE), get milled on every face, angle, etc. just to fit on a fresh block/heads. In extreme cases, where the block deck and head both have been milled, you could mill the intake face of the head, but the intake would still have to get cut on the china wall ends anyway. I would much rather sacrifice a $200-300 intake manifold than cut the heads that could be used on another engine block (and throw the geometry off enough to need extra thick gaskets, etc.).