another sr over heat

[240pav]

ok so the engine was rebuilt and broken in ( according to the lame *** shop )

i get back from iraq and the thing over heats.it has the old ka radiator in it, i know i need to upgrade asap.but it worked before the shop rebuilt it just fine.it take time but it over heats rather quickly, i also took out the thermostat to see if it made a differenct, now it over heats quicker !!i did a radiator flush and fluid change, i also had it on an incline and ran the car saw air bubbles but no real change

could all this be because of a radiator that used to work well ?? would it make that big of a difference after a rebuild ??