That picture in the link you posted is a difficult one to use for details, since it's "washed out" and doesn't show alot of the features.
The Bf109G-2 through G-6 had the "clamshell" cockpit vents on either side and in the same position (like seen in the photo I posted) relative to the cowling/cockpit windscreen. The G-10 and later models had them repositioned because of cowling changes.
You should have one on each side (port and starboard) and they should be in the position as shown in the photo, which is a Bf109G-2.