The Il-2 in AH never had a reflector sight for the pilot. It always had the wires in the windscreen.
Hmm, I could swear that the AH1 model did..
Earlier versions of the IL2 had a PBP or PAK gunsight. They were discontinued from what I can determine due to innacuracies in their function early in the war. Late in the war near the end as supplies of gunsights were availabe and more relyable they began to be reintroduced into the IL2 and IL10. The two circles in the windscreen are the equivalent of the 100Mil and 50Mil rings in the Mk8 gunsight used in USNAVY fighters.
Becasue it's fixed in the windscreen, If you have moved your head position up or down your eyes will not be centered with the horizontal line in the windscreen. Practicing offline against a few tanks convergence at 650 on zoom should help you get the feel for the guns. Those russian air to ground rockets don't work very well for me.
The problem is that, with TrackIR, your head is never in the same place... this serves no problem with reflector sights (which is why reflector sights were used of course) but if there's a physical sight with no reference (a front and a rear sight to work in conjunction as happens on any gunsight that doesn't work of the same principle that a reflector does) you can't use it... you can't get your head directly centered in the middle of the cockpit, you always end up offset a bit. Most of the new gunsights (like on vehicles) that use regular rifle sights have a front and rear sight now... but the Il2 doesn't.
The thing is, that the real pilot must've had the same issue. With just a circle in the middle of the glass, he would have no real way to know where his head was... the circle would be pretty much as useless as having nothing there at all, and just kind of putting the tank roughly in the center of the glass.
This screenshot from the Ubisoft game shows a front sight post in the middle, which corresponds to what you can see on most photographs of wartime Il2's (I would think that ones that don't have this have a reflector sight)

Here's a model...

Photograph of an Il2 showing what must be a front sight...

Also, bustr, do you know what kind of gunsight the rear gun used? Just a PBP-1?