VW Rhino Case Modifications

I have a crack in my MK 9 Hewland case that has been welded before. I am thinking about a re-case. Can someone tell me what is required to convert a new mag Rhino case for FF use? I have access to a milling machine but I am not sure if I am better off just buying one from TRE. They are selling them for $480 and it looks like I can purcahse a new mag Rhino Case for $249-279. Thanks, Joe