Stuart - sarcasm? doesn't answer questions, Waggy doesn't indicate his cooling system "can't handle it"
a 350 running at 200 is not displaying an overheating problem, like 64fleetside sez, they run that way, and using a higher temp thermostat serves the purpose of getting them up there faster, especially with a very efficient cooling system ... but a higher rated 'stat won't necessarily raise normal operating temp, unless it's an engine that tends to run cooler then the selected temp ... like the 235 with a good original system
live in a cold climate and you'll see the difference in a 160 and 195 thermostat is that it takes longer for the heater to really pump out heat, especially with a 235 or 283, not quite as noticeable with a newer 350 .... most 350 applications use 180-195° 'stats and a 16# cap
do the new[ish] engines that normally run above 212 have 212-220° thermostats? what's the highest 'stat available?
Bill