what fluid type to run 727 4k stall

I have used Type F in my 65 Newport for decades since I heard it gives firmer shifts (less clutch plate wear). For daily drivers, ATF+4 should also be OK since recommended for the A-413 tranny in my 96 Voyager, which is the same internal Torqueflite design (other than added differential). Most ATF+4 brands are fully synthetic.