Your t-case will work fine with a 727 from an sii so long as the adapter housing comes with an auto bull gear. In addition to the items already mentioned, you will also need an IH sv8/tf 727 flexplate and crank hub spacer. The bw flexplate and spacer you have now will not work with the 727. If your starter does not have a metal spacer shim between it and the engine block, you will need to source and install one of those for proper starter drive gear to flexplate engagement. It would be a good idea to source the metal atf cooling lines from an sii, since the bw plumbing is different. You will most likely need to do some minor fab work to your trans cross member in order to get everything mounted properly. An sii x-member May prove helpful in this regard. If you can make your current gear selector work with the 727, you won't need to worry about running new circuits for the neutral start system. If you have to swap in an sii gear selector, then you will need to study an electric schematic from a '73 or later sii with auto in order to run the wires necessary to make the nss functional.