Can anyone help me out and give me the measurement from the lower tang to the rear swivel base for a short tang gun? 

I have a 71 that had rough wood when I got it: an aftermarket pad have been added and the rear swivel base had ripped out besides numerous severe dings and a couple cracks.  It was nearly a basket case.  I fitted an original Winchester pad, glued a walnut dutch or patch over where the swivel base tore out and then steamed, glued cracks and tru-oiled the stock.  

Now I’m ready to inlet the deluxe swivel base and would like to place it in the correct location relative to the lower tang.  The requested measurement could be taken to the center of the base or to the front edge, or better yet, both.

Thanks!