Phil, the rad core is 35mm thick.
Here is a picture that better shows the size of the pulleys. If the pump runs too fast cavitation can become a problem. It does have a thermostat.
The engine may well have a larger displacement than the original engine which could explain the larger carb. I have been told that the truck came with this engine ready to install and that the original engine was not included.
I should add that it runs very well but previous owner has had issues with overheating.
Here is a picture of the instruments.
