The main problem that you are dealing with here is the fact that many old bikes had HUGE steps of 2 inches or 5cm between sizes. Today, 2cm increments are the norm and a few brands still offer 1cm increments.

With an 86cm cycling inseam, the range of recommended size, measured center to top would be 56cm at the minimum and about 60cm at the maximum. The general range of standover clearance would be 2-6cm.

You choice of frame size depends on your proportions and how much saddle to bar drop you can tolerate.

Do you intend to keep buying old bikes, or move on to something new in the near future? Newer bikes no longer use quill stems that have a large range of vertical adjustment. When looking at a new frame that will probably have an integrated headset, you then have to consider the head tube length, with the headset and spacers as an indicator the the frame's maximum vertical size. Frame size numbers can be goofy in some brands and no longer match either of the old c-c or c-t methods of measuring. It's a little different ball game than in days past.