Hi,
I urge you to locate online photos of original Virginia guns so you can see what they actually looked like. Do not cut in lock panels except around the front, where a gouge and round file are useful. For the rest, the panels are formed by shaping the wrist and breech section rather than cutting the panels in. Look at the photos below.
The molding lines are cut in after I've shaped the panels, not before to create them. Also note that the bottom of the stock is fully rounded carrying the curved bottom of the fore stock right through to the wrist. It is not flattened. The old time makers did not fuss too much making the panels mirror images. They usually tried to have them start and stop equally so if you looked down on the breech each panel was the same length and position, and any carved beaver tails were centered on the wrist on both side. However, more than that they often did not care. On British guns, the side plate side was often shaped to accommodate the side plate rather than to mirror the lock and the panels were shaped differently as below.
It is usually best to make the surrounding flats very thin. IMO wide flats never look good and are rarely found on original American rifles made during colonial and "Golden Age" periods. Making them thin also helps you avoid carving in the ugly notch for the flint cock you see on so many rifles. Here are some examples.
Finally, on your stock, I would lower the tail of the panel so it terminates either in the center or just below center of the wrist. I would reshape the panels, reducing their size greatly and shaping them so the tails are lowered on the stock.
dave