The decision is made

I'm really interested in how this works out for you. I talked to Art about this same application in my '69 Dart several years ago but haven't been able to put the money together to do it due to several unforeseen "life moments". I've posted several comments on FABO about the benefits of this setup - specifically the fact that you don't have to do any trans tunnel modifications. If I remember correctly, the 200-4R lengthis different than either a 727 or 904 so you'll either need a new longer driveshaft or you'll need to shorten your existing one.
Post up some pics and comments when you do the install. I'm sure I'll have lots of questions for you after as well.
Art's 200-4R trannys are almost bulletproof. Just tell anyone who asks that it's a "custom-built overdrive trans for your Mopar".