<VV> Clutch Adjustment LM Coupe

[rich dixon]

Need some help with understanding the proper method to adjust a clutch. I have a newly rebuilt 66 couple with a new 4 speed, clutch plate, flywheel etc. installed, in the car. It will not go into gear while running, so I suspect the clutch adjust is needed. It was never adjusted per the manual when I reinstalled it. 
 
The Service Manual notes applying a "15 pound force to the clutch rod", am I to assume I'll need a force gage to do this properly?  I ask because I doubt that everyone that's done a clutch has a force gage in their tool box? Is there any other way to go about getting & checking the proper amount of force on this rod without this gage? 
 
Thanks.