engine help

[rdallasc]

we have a 70 gmc with 350 motor
son noticed water in oil, did have bad radiator and since has been replaced.but in the process i belive he got it hot
so we replaced head gaskets, valve job, had heads checked for warpage,"was none"
we drained oil, let sit overnite, replaced oil with engine flush, ran for 10 min or so
drained again and replaced.
still appears to have water in oil!
is there something else wrong or not properly getting water out?
please help

[bd]

How did you determine water in the oil - condensation droplets - mayonnaise - raw coolant in the pan?  Were the heads also checked for cracks?  Is there any oil in the radiator?  Has the engine been run to operating temperature for very long since the repair?  Minor residual moisture may have to be driven off via running the engine at temperature for a suitable amount of time.

Pick up a gauge set and pressure test the cooling system with the engine not running; see how long it maintains ~20 PSI without bleeding down.  Then start the engine cold with the gauge connected to the radiator at zero pressure to see how quickly the system builds pressure.  If the cooling system seal is compromised it will not maintain pressure with the engine off, although pressure loss can result from internal leaks (such as heads, cylinders or intake gaskets) and/or external leaks (such as a loose hose clamp, leaking heater core or leaking water pump seal).  If the cooling system is leaking into the combustion area of the cylinders the gauge will build pressure very quickly when the engine is started and run cold. 

Under no circumstances allow the pressure to build beyond ~20 PSI.