Help with radiator

Put in a new radiator from wizard cooling...that's all I changed...same fan and everything else...I put this NEW radiator good to 600 plus horse to keep it cool...well IT don't..sitting at idel it shoots to 230 and once 250..shut it down...what do u all recomend to do to get this thing to cool....driving goes to 180 on a hot humid day driving goes to 220 tops...but in traffic it will hit 250....
this is in a 1970 Duster...electric fan I tried and wont fit the motor hits water pump pully and no room in front for push////what are you guys doing...wizard just keeps asking question and question...don't think they want to help///so I come to who can you guys...

thanks

wayne