last night I started looking around the qualcomm repos a bit and I think I found the droids we've been looking for.
You probably recognize this screen -
In the qualcomm repos, I found the manifest "M7630AABBQMLZA414005.xml". They name their manifests to match the baseband so it will be easier to find branches and tags and crap like that. I didn't find any manifests that start with the "M8655" like ours. There are lots of tags that start with that in the M7630 branches, though (M8655AABBQVLZA31361005). The next little part that doesn't match up is the "ZA". Ours has the "YM" at that spot. I still haven't run across any with the YM. This was one of only 1 or 2 that I saw with the "414005" at the end.
At any rate, I think this confirms that we do have the msm8655 and not the 7630. Wen I get this manifest, the code in vendor/qcom/android-open/libcamera2 matches up with our stock libcamera better than any of the other versions I've seen. Our stock one has some LG-specific stuff in it that they added in themselves. The frameworks/base/telephony/java/com/android/internal/telephony stuff matches our stock framework.apk 1000x better than the tangled mess that is cm7.
So, I'm gonna try building this one here in my crappy laptop and maybe it will run. If nothing else, it should give us code that works with our phone better than whichever of the thousands of versions of the qcom code happened to end up in the cm7 tree. You might have a look around and be able to figure out exactly which manifest LG used as a starting point.