727 yoke engagement

Thomas Davey said
...........Will an inch shorter hurt?

I'd think an inch less spline engagement from stock might translate to vibration (one of those ya' can't seem to find) and eventually fail on you.
Maybe measuring using this order form can help you decide...……….
http://www.dynotechengineering.com/...m/adobe/1 pc driveshaft trans to cl.pdf?la=en