Swirl Port 350 overheating problem

[Jackal2k9]

I dropped a swirl port "vortec" 350 into my 70 cheyv truck and it over heats. Its a motor out of a 94 suburban. I used the cylinder heads but put a performer intake and a 600 edelbrock carb on it. The water pump is the multibelt accesory drive system (old stlye stuff). The temp reads 240 out of the motor, 130 back in at idle, and 240 +plus on the mecanical cylinder head guage. On occasion it boils water and spikes heavily. I have replaced radiators, water pumps, hoses, thermostats, added dual trans coolers, run advanced coolants, used synthetic oils, set and reset timing made carb a tad rich, check relief cap, run with out a thermostat, restricted exhaust a little and beat my self up for countless hours by doing all this. Overall effect - 10 degree drop in temperature. Why does it overheat? Is there some problem with these heads and my intake getting water logged from crossover? Is ther some trick someone knows to fix it. i do not think this is reverse flow motor. Those were only lt1's and such.
nethings more than what i know about why its doing this.

Thanxs,

[Stano]

It is a reverse flow motor. The water pump with a serpentine belt drive on 88 and up were reverse. Big blocks too. could trickle down into 86 when they were switching over to TBI. Know several people who have used the wrong water pump in their serpentine belt trucks around here. But as long as you are using old style waterpump and all shouldn't be a problem. If you are using the later style pump the impeller is turning the wrong direction. Also make sure you have the right fan for the application because the later one are running backwards too! Hope this helps out.