Type F is what is used in a Ford C-6, I build many of them.
I would even think if you used dex or merc it would still work just fine.
I word use a synthetic ATF, make sure you drain the convertor it has over 5 quarts in it. look for a 7/16 head plug next to the convertor flexplate bolts
Its a C6. It doesn't care by now. How many times has it been rebuilt? what upgrades?
Any dex/merc or equivalent will work. I think I topped off my leaky c6 with just about anything I could find in the garage and it wouldn't quit....psf, hydraulic fluid, motor oil,.....
It all depends on how much you want to spend.