fluid type for A-518

i just recently had an A-518 transmission fully re-built by a local shop in my area and i have been trying to figure what the best fluid to run it would be?
Its has a non lock up converter, i do not have a shift kit installed yet, but i will eventually be getting ether a transgo kit or a b&m kit put in it, i have a transgo an B&M kit just have not had the time to put one of them in and have not decided yet on wich one to run.
I was strongly thinking i would run atf+4, untill i was told by a few transmission people i know that it wasnt what they would run, i was told there are too many friction modifyers in the +4 to use in a non lock up A-518 and that it would make it shift poorly and run hotter, it was recomended to me that i run reg dexIII or the new dexronVI, or if i wanted to run a synthetic then to use amsoil or royal purple max atf.
What i wanna know is if type f atf would be safe to use? my old man ran type f in his 727 with great results, but it had a shift kit and higher qaulity parts in it. What i want is firmer shifts and a more responsive transmission, i realize this is hard to do without a shift kit, but like i said it will be getting a shift kit, the main question i have is what fluid is the best for this transmission? i would like to run type f but i just dont know if it is capable of keeping the overdrive unit happy because i know the overdrive unit creates more heat.
Anybody with suggestions or recomendations or experiences with diff fluids in this particular trans please share with me, its the A-518 not the 46re, i think the only thing electronic on this transmission is the overdrive, wich i plan to wire a toggle switch too. thanks in advance to anyone with some ideas or suggestions.