I made a similar swap a few years back. Used a hydraulic roller cam and made lots of horsepower and lots of heat. So, at the same time I installed the engine, I also installed a triple pass radiator like this one:
http://www.summitracing.com/parts/aaf-all30045
I had a couple of problems with overheating after that. The worst was because the intake manifold bolts loosened and allowed air to be sucked into the intake. I suggest that you use Indian Head Shellac to seal your intake gasket and check every so often to make sure they stay tight.
The other problem was caused by the thermostat being too small (only on a hot day). I had to find a larger one, I believe that I ended up with 15/16" hole.
I also found that water mixed with the most expensive Prestone
antifreeze allowed my engine to rust internally. I flushed all that out and use 1 and 1/2 bottles of Redline Water Wetter and distilled water only. After I purged all the air out of the system, it stays cool unless I am creeping slowly, like in traffic.
My electronic thermostat starts the radiator fan at 200 degrees and is able to keep it there. I have tried to locate the temperature sensor probe for the fan switch in different places. I have found that the best place is near the outlet tube at the bottom of the radiator. If you put it near the input, it runs too much. It will even run your battery down if you don't shut it off when you park. At the outlet works much better and I actually wired it so it does not run when I turn the engine off.
These are lesson that I learned the hard way, I hope that they help you.