1970 727 Just Finished Rebuild-Suggested Fluid?

[7E-Bodies]

Just went through the numbers matching 70 727 yesterday. What's suggested for transmission fluid these days?  Original? Synthetic?  Going to sit on the shop rack for maybe a year. Only plan to put in a quart or two so it's not oozing out the tail shaft, then roll it a time or two on the engine stand. .  Also, the dipstick tube seems a tad loose where it enters case, even with new o ring.  Inners are sufficiently greased in anticipation of sitting a year or so.  (Friend that has owned a transmission shop 30 years led the job).  Thanks in advance.

Kevin

[Chryco Psycho]

I would suggest F type or B&M Trick shift
I have not tried ATF 4 in older trans but ATF 3 is fine also 

[1 Wild R/T]

I would suggest F type or B&M Trick shift
I have not tried ATF 4 in older trans but ATF 3 is fine also 

  Type F...