[A1971Blazer]

In past experience........those 454s tend to run hot a little hot....I had one years ago that wanted to overheat.....I threw money at the radiator to no avail....finally ran across some info (this was pre-google era) about putting a slight restriction in the cooling line where it went into the top of the radiator..
I made a do-nut type washer with a small shoulder machined on it to secure it right at the hose connection.

I can't remember the exact size.....and IIRC I made several before I got it right.............but what happened was, the thermostat opened at the same temp.......but the restrictor slowed the coolant flow enough to allow it to absorb a little more heat as it flowed thru the motor.....it worked......dropped the coolant temp about 20º.......still ran at 205º

If you're running an auto tranny......and you probably already have one........but you for sure need a heavy duty auxillary tranny cooler......that trans will get hot.......especially when towing.