[Arran]

Ron;
  I guess I missed that part about the spot of wax, at least it gives you a reference of where to put the hole. I wonder if the production 42-720s, if it ever made it that far, used a different chassis and or power transformer? It looks almost like they used the same iron cores for that transformer as what they used for the 42-380 style chassis, but vertically mounted, since the wires all come out the same side. It's curious that Edcore can't make a narrower transformer, maybe they are concerned with core saturation more so then Hammond? But from what I heard Hammond tends to underrate the current and primary voltage ratings of their transformers, what I can't stand are those cheesy plastic tags they glue on to their transformers now, the old ones had a nice metal plate riveted on. 
Too bad that you are in Indiana, I could lone you a Greenlee punch to make that extra hole rather then you having to flog one out with a file or rotary tool. I have an incomplete set of those punches, though I have most of the important sizes, sometimes they have sets on fleabay for good prices, but it only makes sense to buy if you do a lot of this sort of thing.
Regards
Arran