Your blank may have lost some figure during turning, but that is far from being what I'd consider one sided. It's a great looking stock. There is no way that I would consider a grain painting enhancement on that piece of wood.
In the event that turning really did make a very nice blank one-sided, I agree with Clapper Zapper. That would be the time to cut your losses, sell what you have or use it on another project, and buy another blank. Considering what grain painting enhancement costs, there probably wouldn't be all that much difference in cost if you are a smart wood shopper. And it would be real. Another consideration is the grade of the gun. To me, an exhibition grade stock looks out of place on a low to mid grade gun.
The grain painting enhancement process may be preferable to looking at a glue joint between two entirely different pieces of wood resulting from a repair, or adding an extension to increase LOP. But I have never seen a grain enhancement job up close that would fool me into believing it was real. And it seems that the more enhancement that is added, the more fake it looks... like a girl with too much make-up.
It would be interesting if you had some "before" photos of the blank to show us what it looked like before turning.
