Tranny and Engine cooling (BBC/TH400)

Didnt know which forum to post this in. Part transmission question, part BBC question....
I recently purchased a 3-core radiator to cool a BBC and replace the old 2-core that I got with the car. The dimensions are about the same due to the fact that it has three narrow cores vs two wide cores. He (salesperson) also pointed out that it has more fins/inch^2 than the old radiator. Does this sound correct and should that provide the extra cooling capacity I desire?

Second, another person recommended not using the rad to cool my ATF fluid and go with an external cooler. My radiator has the fittings but I also recently scrounged an external 8x10 tranny cooler from a ford econoline van. Any recommendations on one method over the other or should I use the 8x10 to supplement what cooling the rad will provide? My theory is that many a car runs with just a radiator to cool both engine and tranny without a problem, but, when I pulled this external one from salvage, I noticed that the factory setup put it in series with the radiator.

Opinions?

Techinspector: If you are listening...this is the last item I needed to get my BBC going. The last "to do" on my list is to check the pressure on my valve springs (so I dont flatten my cam) and then we can continue our discussion from a few weeks ago.:)

The cooler in the rad works better in cold weather. It actually heats the trans fluid so it flows better. If you drive in really cold climates its better to use it in series with the one in front of the rad.

Thanks Pope, but shouldnt I avoid the external cooler based on what you said?
btw: I would characterize my climate as 90-100 summer and 25-45 in the winter (midwest)
I guess I will plumb it up with just the radiator only and see what happens. Winter is about here so I think if I will have problems, they wont appear until next May or so. I was just looking for opinions since engine/tranny cooling seems to be a big problem for some people and not for others.