3 prong range outlet
For an old installation, there are some "shortcuts" grandfathered in, but even those are based on "no ground but have a neutral". You have the opposite - and much worse - problem of "no neutral but have a ground".


Rip out the 8/2 and put 8/3 in place. That will give you two hots (typically black &amp; red), neutral (white) and ground (bare or green).
Replace the 3-prong outlet with a 4-prong outlet NEMA 14-50. This has connections for 2 hots, neutral, ground.
Replace the 3-prong cord with a 4-prong cord. You will likely have to make a small change inside the range to separate ground and neutral.


What you have right now is unsafe on many levels. It happens to work because on a typical range the neutral carries relatively little current most of the time. But it violates code in several ways:


White should not be hot.
Ground and neutral should be separate.
Neutral should be white or gray, and definitely never bare.
New installations should always use a 4-prong outlet.