have you done a pressure test on the cooling system to check head gasket integrity? not that this is a common issue with a SBC, but it might be worth a look.
Also, why a 160 t-stat? those are for race motors. you should be running at least a 185. I like the 'balanced' t-stats from robertshaw or milodon.
1994 FZJ80. Elocked, MAF 3/2 Lift, BFG 315 KM2s, stock 4.10s, ARB bullbar and a Warn 8074 winch.
powered by an all-aluminum 335hp L33 Vortec V8
2004 Kona Stinky dee-lux.