What's missing? 727 BB

I'd also recommend a complete core for your first trans rebuild. All the parts will be mated. Just makes things easier. That said BB cores do not grow on trees. You can certainly get pretty much anything you're missing. The ASTG service manual is under $30. Also check out Wit Trans website. They have a nice 727 breakdown. Click on any part to see cost/availability.

https://www.wittrans.com/Schematic.aspx?Transmission=A727