I have my doubts about temps of over 200. We used GMC's in the 50's and 60's as work trucks and ran 50/50 anti freeze. We never used Chevs because my uncle sold GMC's. We had lots of heads to crack into the exhaust valve seats. We built fan shrouds out of a 14 gauge sheets, cut a hole a little larger than the fan and bent a hoop out of 1" flat and bent it into a hoop. It kept trucks with a 180 thermostat from going over 190 and put an end to the head cracking. I did the same in the GMC's I hot rodded. I really don't think the inliners were built to run over 200. Boiling which puts air bubbles in the coolant passages creates hot spots, but our experience with over 200 was not good. In addition to cracking heads, engines that ran over 200 used oil prematurely. If you intend to pull a trailer, I would really recommend a shroud. Especially because you are pulling a lot more HP out of it than the factory designed into it.
