Help my 1969 Plymouth Satellite roadrunner clone is overheating?

i just put a used waterpump housing but a new water pump and thermostat. it seams to overheat really fast so i took out the thermostat and it didn't help. so i took off the radiator hoses and flushed everythign to make sure there was no blockage. could the waterpump not be flowing like it should any help would be great i have to start driving it daily as my minivan died so please help. i know it dont make a differnce but it has a 509 cam edel. 600 with 1/2 in fuel line and carter ele. pump. 200 shot of juice "that has not been ran yet" 323 sure grip out back with a 3000 stall in the 727 .