Slip and slide transmission

Ok, been doing some research. Looks like the 904 used with the 273 came with the single wrap rear band. Some threads indicate that the double wrap requires a different case? So do I need to keep what I have, or can I upgrade to the double wrap with the stock case?
I believe thats only with /6 904s. V8 904s should have a double wrap cast band, someone please jump in if im wrong here. Make sure you get a red lined cast double from a&a. These are the two I use.
904 2nd Gear Band Red Racing Solid with Grooves *1.375" Wide - A&A Transmissions *2nd Gear Band
904 band - A&A Transmissions *Reverse Band
If its actually a single wrap, then this is what I would use.
904 Reverse Red Racing Single Wrap with Grooves core $25.00 added - A&A Transmissions