Chevy 400 sb cooling headaches

[rickpilgrim]

After 3 yrs of running our 93 K3500 dually on 511 cid Caddy power, fuel prices dictated a change to cheaper running engine(over 8 mpg). We found a good running 1972 400 sb Chevy w/71K orginal miles from a wrecked kingswood estate sw.30 psi oil pressure after 40 min run time @ 180 degrees, no bubbles in the coolant. It leaked oil everywhere, so we tore it down to a short block, installed a new oil pump, an all steel oil pump driveshaft, new frost plugs, comp cams extreem energy 212@.050 cam&lifter/ timing chain set @ 0, Fel pro gasket set(for 400 w/steam holes), new valve seals, port matched the heads, offy dual port intake, msd street fire distrid w/accell cap,33 degrees btdc @ 3500 rpm. 1.52 semi roller rockers, Wieand aluminum water pump and moroso reverse opening 160 thermostat. OE diesel oil cooler,radiator and 3/8" fuel lines and Holley red fuel pump and 650 holley spreadbore carb. 2-16" electric fans and 22psi rad cap. All the cooling parts cooled the big Cad with 10K lbs on trailer on 90 degree days.
Now that it's 65-75 degrees here the 400 runs HOT, at 230-240 when towing and has hit 245(where the safety system shuts it down) and is never less than 210 when towing after 5 min. I have a 160 amp old school caddy limo alternator and dual batteries or the fans would overwhelm the oe alternator.
The 10w30 oil got so thin after a week that I can hear the rods when warmed up with the stethiscope.
At this point I'm ready to make whats left into a vortec 383 unless anyone has a good idea on what could cause this.