from big block to small block

recently swapped out a 454 for a 350. Is the radiator from the big block bigger then the small block radiator..

I was told that the rad might be bigger and this could cause issues down the road.. It seems my motor never warms up at all and if it does it takes for ever. I was told this could lead to performace issues and excessive moisture to build up.

Put in a 180 degree thermostat in the waterneck. Water temperature in the radiator will then be irrelevant.