SBC .060 overheating problems. Suggestions please!

[72tutone]

I have researched the site and have googled this topic but I need some real feedback.
I have been trying to break in my new motor. SBC .060 alum heads, edelbrock intake, holley 670cfm.
I'm running into serious overheating problems. I can get to about 5min or so breaking in the cam, and then i get heating problems and it boils out of the rad. I hate keeping to have to stop and start the motor like this. Granted when it does start we have the idle screw cranked up so its not really idling at all.
I have a stant 180 thermostat, stock 3 row rad and a 16" jeep fan with factory shroud. This thing pulls like 3000cfm.
I'm running a serp setup out of a 94 blazer with a new reverse rotation water pump.
I have the fan running all the time and the top hose is getting hot so the thermostat is opening. Just to be sure I boiled it and its opening as it should.
The lower hose isnt collapsing that I can see. I'm not sure what else it could be.
Could the rad be the problem? Ive already taken the water pump back and exchanged it out for a new one. I dont think the stat is the problem, or water pump.
Process of elimination would be the rad. Its a 16lb cap if that makes any difference.

We did have the bypass hose hooked up from the intake to the radiator. Thinking the hot water was running back from the bypass hose back to the rad, we plugged the hole in the intake and then ran the hose from the rad to the water pump. I'm not sure if any of this is necessary or not. I do have a factory AC but its not hooked up at all.

Could the rad be the culprit? Its the only other thing I can think of???