Tram Gauge or plumb bob?

[Doug1]

I need to check some measurements to make sure the subframe is square up and realized a tape measure doesn't make a good tool for the job without getting the measuring points down to a place where the tape can be kept straight.

So either I get a plumb bob and mark spots on the 4 post lift or I build a tram gauge and use it. The primary factory measuring points on the 2nd gen are the center of " 5/8" master gage holes" so there's already some room for error, since you are supposed to measure to the center of a pretty big hole.

Which route works best? A plumb bob might be the easiest route but a tram gauge isn't all that hard to put together either.