CAT MXS ACERT Overheat

Hello, I have a 2007 International with a Cat MXS ACERT Motor in it. We had an engine overheat on it a couple weeks ago and cracked the head and took out the head gasket. We had a local shop who has always done good trustworthy work put on a new head gasket and head. Also previous to this all within the last 2 months we have put in new thermostats, fan clutch and a reman cat water pump. After having all this done and bringing the truck back for a test run it continues too overheat on long pulls. We thought possibly the gauge or sending unit was out considering the gauge would jump and spike all of a sudden but after replacing both of those it still isn't the case. Any ideas? At 80,000 on approximately a mile long pull it slowly rose to 230 then hit 260 within seconds before us shutting it down. This also was with the fan on manual to begin. Any ideas or suggestions would be appreciated.

 

When you say the radiator assuming I pull the lines off the top and bottom and put a hose directly in the top and water is flowing through as fast as I put it in what more is there to check from that standpoint? I will investigate the hoses themselves for possible collapse soon as the truck makes it to the shop. I also do not believe the fan clutch is bad or that the belt is slipping but I will check them again. Is there a specific way to check the radiator itself? Thank you in advance

 

Is there a way or port to check pressure of the water pump? I am open to anything at this radiator and CAC have been thoroughly clean and are not plugged with debris. Both radiator hoses are warm and the radiator itself feels to be a uniform temperature. I have verified gauge readings with CAT ET also.