So I've done a bit more opamp swapping with the newly modded 797Bs. I've tried the following in the LPF stage with 797s in the I/V stage:
LT1028, LME49990, LME49720NA, OPA627AU, and OPA627BM.
The LT1028, LME49990, and LME49720NA all sound good.
However, the OPA627AU adds an extra level of detail to mids and highs.
The OPA627BM further improves on the OPA627AU by adding a slightly better sound stage, more bass impact, and lower bass extension.
I also tried modded AD797B, they sounded similar to the OPA627AU with one problem. A distinct wooshing sound when no audio is being played. To me this indicates that even with the mod the AD797 is still unstable in the LPF position.
Again this is just my opinion, everybody has different tastes/hears things differently.