I have had my 72 Scout for 23 years with a lift, 33" tires, 392, 727 automatic. I do not have a trans cooler (never have) and have had no problems with it at all. I don't typically use it for heavy wheeling / towing, so see no need to add one in. If you are doing heavy wheeling / rock crawling or a lot of towing I would recommend one.
Electric fan is another option. Most folks who put them in remove the stock fan and run electric (taurus) fans that are wired to kick on as temp comes up. I'm sure a quick search here or on binderplanet would yield a wealth of information on this subject.
Cheers,
c-