PJ, didn't we just do this topic with you a couple of weeks ago?...thought you had all the info needed for sorting this out. Anyhoo, like i mentioned before, if the CTD's only happen in QC and missions with your wingmen flying the same model, its the lightstates. If it happens in QC and missions even when you fly solo without wingies, then you have a deeper problem. The fact that your problem continues after you edited the mdl -- i presume with a hex editor or scasm -- suggests that maybe you left something unfinished in the editing. Beyond that, maybe we need more details on when your sim crashes. Does it happen (A) when you select the model from the list, or (B) as the mission is loading after selecting the model or (C) after the mission has loaded and you're sitting on the runway prior to takeoff or (D) at some point further into the mission as you're operating. Going further, are you certain that the problem is the model and not some format error in the mission itself? Using an alternate model with the same loadout in the same mission would clear that up.
If you're 100% certain that you've edited the conversion properly -- and the alternate CFS2 selection works out OK in the testing -- it could be an error in the dp format. Take the dp from the alternate, drop it into the conversion's folder and rename it as the conversion's dp. Don't try to edit anything like mountpoints and gunstations in it to fit the convert at this point, just use it as-is. If this works then you know that you've got some dp work ahead...