727 build advice

[Calif240]

Guys, I've got a small block 904 combo in my '69. I'm going to be looking to go to a 440/727. I'm looking at building a 727 from the ground up and was hoping to get some advice on what to start with? Should I look at getting a stock housing and then buying all of the aftermarket parts to build it? Should I get a complete 727 to use any internals? It's gonna need to be rated around 600-700HP. I'm still doing some research and it looks like I can use any 70s 727 from a passenger vehicle w few modifications. Any advice or thoughts are extremely appreciated.
Terry

[70 Charger RT]

If you find metal filings in your pan, i would pull the trans and do an overhaul.  More than likely if you find filings your rear sprag one-way clutch is toast.