If the engine was rebuilt, including boring and installing new
pistons, it is gonna run extra warm for the first 15-20K miles. This
is due to the close piston/cylinder wall clearances. Its a little late
now, but a piston clearance of .0025-.003 would have made it run
cooler from the first mile. An oversized radiator, possibly an
aluminum one, would probably help more than anything. If you gotta
have one of those original six blade fans, I have one we can talk
about, reasonable.

  Joe Hall