How much heat

If the cooling system is correctly designed and operating, the engine should run within a few degrees of what the thermostat rating is. If he is running 190-200 degrees with a 194 thermostat, that would be right in the range. If he is running a 160, I'd say there is a problem there. If he has a 180 in there, it tells me something is not quite right, but, not a problem at the moment. Depending on the ambient outside temperature of course, but, assuming it's not 110 in the shade, either there is a coolant flow problem, air flow problem, heat transfer problem, or, capacity problem. Knowing the temp at various stages and speeds can help determine which problem he may have. If it's just while in slow speed traffic that it heats up, it's usually an air flow problem. Sometimes a shroud or higher capacity fan will help. If it's at freeway speed or going uphill under load, it's usually a flow or heat transfer problem. If the temp just keeps rising as you run it under "normal conditions" it could be a bad core shift in the block where the coolant boils in hot spots before it gets a chance to cool. You see that a lot in overbored engine blocks where the cylinder wall(s) gets too thin. Some overheating problems can be overcome by changing components in the system, but some, like a thin cylinder wall can't without changing the block or sleeving the offending cylinder wall(s).