The difference between a right- and left-handed VM is the location of the idle speed screw. The air screw is always on the right side. Look at your right carb. Note the idle speed adjuster screw is on the right side, easy to access. Now look at your left carb. Were it a true left-handed VM, it would have it's idle speed adjusting screw on the left side, the "outside" when it's mounted, so it would also be easy to access. It's on the inside, the right side of the carb, and that makes it a right-handed VM. There's no issue running them, it's just harder to adjust the left one.