56 truck heater hose routing - overheating

[BS Stuff]

Trying to figure out why this truck gets hot and spits out before circulating / thermostat opens. Wondering if heater hose routing can make a difference?? Heater hose off manifold versus off water pump to special side of core ??? Drained block, all coolant flushed out and all hoses off / flushed. Was new engine and radiator 10 years ago but never put in or ran. Did not find hidden nests, etc.
56 Chevy Panel Truck
Targetmaster 350
Stock style 3 core radiator
Deluxe heater with new valve and recon core. Valve worked properly before installing.
195 Degree thermostat.
14" Electric fan with temp sensor kit - note - it kicked on fan right as spitting / puking started. Engine was ran long enough before capping so should have been no air in system.
Thanks !!