Although not every La-7 had it, many of them where equipped with the AG-2 attitude indicator (the same one used on the Il-2, Pe-2 and MiG-3).
There’s a pretty big space unused on the top right corner, next to the radio compass, of the in-game cockpit that corresponds with the artificial horizon indicator placement.
I think, at least, the La-7B model should have it, not only it’ll be great attention for detail, but also it’ll change things around a little bit; most soviet WW2 fighters had rather rudimentary instrumentation and lacked an attitude indicator, the MiG-3, Yak-9DD, Yak-9MPVO and La-7 being the exception