I put a 360/999 combo out of a 79 Cordoba in my /6 72 Dart. originally it was a 2bbl 360. Put in a 340 cam, added a 4bbl, had fun for years. No problems. My advice is to just swap it in and run, if you decide at some point you want more you can worry about that then, trust me the stock 360 will be a very nice improvement over a slant.

Two things, are you sure it's a 727? And you will not be able to run the Cordoba's kickdown setup, it's hit the firewall before full throttle.