If you have NOTHING hard to not go with a Turbo 400.

Look at it realistically. A shifter is a shifter, a converter a converter, valve body, etc so those parts are a wash on cost. A turbo 400 core for basic parts will likely be cheaper than the 727. You buy a Reid or ATI case with a Mopar bell, no adapters needed. Nor will you need to buy shields or blankets to cover that 40 year old stock case.

Now, if you have a shop full of 727 parts, it's hard the justify the 400 at your power level, but if not, 400 is the easy choice. Better trans, better converter selection, better parts selection