66 Dart, 408 runs hot. HELP PLEASE!

My combo works great, and since a lot of people have issues, i thought i should post it. 408 stroker with a 235/249/107 comp Thumper cam, airgap intake, 1 5/8 stepped TTis, Mopar vacum advance dist with 14 initial and 30 total with EQ heads, 504 hp, 3.55 gears, auto with a tight ten inch converter.
I cut the radiator opening extensivelyly to allow a 26 in 3 core Champion radiater to fit, and modified the radiator core support to move the radiator away from the fan as far as possible so i could use a clutchfan with seven blades, no shroud. I ended up with 1/2 inch fan to rad clearance. It took removing a lot of sheetmetal from around the rad, and i had to weld in flat sheet metal for mounting the radiator further forward. Regular bypass hose in place, a good water pump, but underdriven about 20 percent by polished aftermarket pulleys.
What i ended up with is a system that runs at 160 with a thermostat in place, won't go over 170 to 175 on a good gauge no matter how hard i drive it. I hope this helps someone out there.