i have a overheating problem on a 87 b2000 motor, just replaced the head and got all running great, but then started overheating...any ideas

Did you replace the thermostat? Was there any stop leak in the cooling system before you replaced the head? If so, you're radiator may be plugged. Is the fan pulling air through the radiator good? Maybe there is debris built up on the front of the radiator. Since you just replaced the head, are you sure the head gasket sealed? Do a radiator pressure test to see if it holds pressure without the engine running. Also check the radiator cap to see if it is still holding pressure to whatever the rating is on it.

New Rad Cap, New Thermastat, Radiator Is Flowing Good, Didn't Run A Presure Check, Will Do That...no Stop Leak...all New Hoses...got Me, Unless The Head Cracked...

unless it has been replaced on that model with a timing belt the water pump is probably bad mine acted crazy different temps all the time then the water pump fell apart

Another possibility ,,,,,,,, sigh happened to me with an 87 celica ,,,,,,, they shaved the heads down to far thereby creating more heat that cannot be carried away by mere water ........... take thermostat out and see if runs hot at idle {worst case scenario},,,,,,,,,,, You already made mention water is flowing across radiator,

Is the air vent on the thermostat at the 12 O'clock position? What percentage of water to anti-freeze are you running? Have you checked ignition timing? Taken the fan shroud off and blasted through the back of the radiator with a hose to get all the bugs out of the front? Have water leaking out any of the core plugs or comming out of the recovery bottle?

Where is your temp running on the gauge? About 1/4"-1/2" is normal, most trucks run closer to half.