According to TURTLE :

Is it legal to combine the Neutral and the ground at the receptical behind
the stove and not go all the way back to switch box with the extra ground or
neutral / making 4 wire system Hot,hot,Ground, and Neutral?

I would suspect _not_, because having the four prong plug will be misleading.
Perhaps not "illegal" per-se, but an inspector wouldn't like it.

Besides, it's usually very difficult to pigtail #8 or #6 wire inside the
outlet like that.

I wouldn't install a four prong outlet & plug unless the circuit really was
four wire. Three wire stove/dryer circuits are still legal for "old construction"
(down there), so I'd stick with three prong unless you really were upping the
circuit to 4 wire.

New construction, of course, must be 4 wire.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.