I'm not sure if this could work, but try using ps3 game convert instead of cfw2ofw helper, it asks you to give the update manually, so you could try that.
If it works let me know btw
Fallout new vegas is difficult to play without the disc even for cfw users. It took me alot of trial and error to finally get it running and that consisted of leaving it in folder format and putting it on the HDD. If I converted it to iso or split iso always got the same results (a black screen) you are better off just playing it from the disc.