cooling system help

i have a chevy 350 block that is currently running at 383.  it is running in a 92 chevy k1500 silverado.  the engine has shorty headers, a custom air intake with the stock TBI with new injectors, a high flowing intake manifold, cast iron heads(not the originals but from another engine).  it originally came with a mechanical fan attached to the same pulley that the water pump is attached to.  i recently tried swapping the mechanical fan for an electric fan rated at 2300 cfm.  i put on all of the necessary equipment to run the fan.  i drove the truck and only got about 50 feet before the engine overheated and i had to shut if off(and push it home).  the next day i rewired it so that it came on whenever the engine was running.  the same thing happened.  my cousin told me that i didn't have enough air flow from the fan and that upgrading to a higher flowing fan would stop the problem.  i found a 3000 cfm electric fan on summitracing.com and made a mockup out of cardboard.  i have enough room for two of them side by side.  i wanted to know if two of these fans would work before i spent my money on them.  would 6000 cfm really help with the overheating problem my truck has with electrical fans?

P.S. the radiator is larger than stock and the fans are 12.5 inches overall diameter.  

When you built the engine, did you change water pump or belt system? The reason I ask is because a serpentine belt water pump spins backwards from a V-belt driven water pump and that would allow it overheat. When you tried the electric fan, are you sure it was running in the right direction? I do beleive your original 2300 cfm fan should be adequate and certainly shouldn't have overheated within 50 ft. unless something else is wrong.  

I agree with JW above, it sounds like you've got a water circulation problem, not a cooling fan issue, or the fans are spinning backwards.

Was the motor overheating with the stock clutch fan?  

"Was the motor overheating with the stock clutch fan?"

nope.  even in 4wd it wouldn't go above the 280 degree limit on my temp gauge.  it is a serpentine belt system.  my theory is that the water pump can't flow as high without the fan as a counterbalance on the pulley.  could that be correct?  or is something else wrong?  i'll check and make sure that the fan is blowing air in the right direction.  

Have you checked to see if the water is flowing by looking into the radiator while the engine is running? The fan has nothing to do with the water flow through the pump. This is rare but a friend ruined a motor when the impeler inside the water pump fell off, he didnt look at the guage until it was too late. Also I used 2 13 inch fans on my Chevelle with a new radiator they worked marginaly, they kept it around 210/220 in the summer. I tossed them on the shelf, installed a brand new fan shroud and good old X fan now it runs 190 all the time no trouble since.