I have never cut a handle off any #5 of mine, but most short tangs have had enough weight in back end to balance weight of blade plus guard with center of gravity either at index finger or at guard. Assuming a normal proportion tang circa 1/2"x1/4", I could see about 3/4 of handle length. The back part of tang/handle takes very little stress and think anything past 3/4 main need is for a pommel hangar.

Nice knives there, Bill. I would be scared to death of the 8 option jobber but a rarer and rarer thing and a beauty. If someone has posted a 9 option #5 here, I do not recall one and have watched this site for a while, long enough to see many early posters no longer here, and they had some humdingers.