In my totally unprofessional opinion cylinder throats size is the only issue of concern with the 29-2s. Buy a couple of pin gauges and measure before you buy. I would personally pass on any gun that measured over .430 - .431.
Check the barrel cylinder gap, make sure they are not touching. An old way of checking for proper spacing between the two was to fit a matchbook cover in. Should be snug and not loose. Also check the cylinder for play, front to back and side to side movement should be very little. Cock the hammer and see if you can push it forward will a little pressure.