[1956cameo]

I'm not exactly sure why you are having so much trouble but here are a few things I can think of. I drove a big block 70 for years in the Texas heat and rarely got over 200, and usually ran around 185 in the summer. Do you have a big block radiator, or radiator built for small block? Also is the radiator new or is it old and possibly got blockage? Also I always run my trucks with the manual fan off the water pump. Do you just have the electric fans? My trucks always seem to run warmer if they just have electric fans. The only other things I can think of is that possibly your water pump is worn, or you could try and put a cooler thermostat in. I usually put 160 degree thermostats in my trucks. I am sure someone else can help you further but those are the only things that come to my mind. I put big blocks in all of my stuff and they usually run cooler for me than small blocks.