I had made a thread about the v8 ota just for questions like this
If you have CWM installed, it almost always makes an OTA installation fail. I checked on v7 to v8 just to be sure for this phone... it failed.
Since this rom isn't based on stock you would have no need for the OTA block. In fact, the file that the OTA blocker removes doesn't exist on non-stock roms (CM and AOKP, AOSP if it ever gets going on here). So all the OTA block zip would actually do is clear your caches for you, and probably spit out an error about the file missing.
Hopefully that clears it up for you a bit.