I've learned standover is just one measurement, and agree that you also need to worry about the reach. I'm a good example why those charts are only a starting point. I'm 6'-2", which Trek's tables say is an XL frame. But I have short legs (31.5 inseam), which the charts say is a medium frame. Combining those dimensions in the Trek calculator gives a large frame, but some of their large bikes have standover heights that are uncomfortably close to my inseam, others are less tall. The reach varies as well. So I'm going to have to test ride, and that may be months before they get something in stock. The new bike I want (the FX 3) isn't in stock until April.

In your case I think you are going to have to look up the specs of any of the used bikes you are considering, and then maybe get some help on the Fitting Your Bike forum here (sorry, can't post a link because I have less than 10 posts, but just search under Bike Forums).

Mark