The temperature does seem to be getting a little too hot (from 160 to 220 on one run), but a lot of heat build up usually comes from the torque converter slipping too much. What stall is your converter and how much does it seem to be slipping with the big block? What is the size of the cooler on the firewall? (I have mine mounted about 2" away from the firewall and it is 15x7) Make sure that the cooler isn't clogged or that the lines aren't pinched or clogged. (I run #6 steel braid line for mine) Do you have the deeper aluminum pan? This will add strength to the case and also 2 extra quarts. What size converter do you have and how long are you "on" the converter before making your run? (I don't floor my car and go onto the 2-step until the 2nd yellow goes out.)
Bill M