What was the original application for the engine, and when was the block manufactured? Prior to about mid-year 1956, the only engines with an oil gallery connecting all the lifter bores were passenger car engines with Powerglide transmissions. They ran hydraulic lifters. Trucks, and standard trans cars did not have the big gallery bored front to rear to oil the lifters. Around 56/57, all blocks got the big oil passage to the lifters, regardless of transmission or lifter option.
Engines with the oil line from the rear cam bore to the head DO NOT have that big gallery, unless they also have hydraulic lifters from the factory. The engine/trans assembly I just acquired a few days ago turned out to be a 1953 passenger car 235, with a serial number prefix indication it was originally installed in a Powerglide-equipped car. It was married to a SM420 truck 4 speed transmission for an early 1950s truck with a torque tube rear end. Definitely a mixmaster! There's no telling how these old engines and vehicles were swapped around in the past 70-something years!
Jerry
