I am tearing down my 56 292 Motor to rebuild it. When I pulled the Motor  5 Years ago to re-seal and Paint it I pulled the Pan. Bearings are original Standard size Ford Bearings. The Timing Chain was just about falling off so I replaced. I thought this Engine was original based on the Bottom end. When I pulled the Heads this Wek imagine my surprise It had the bigger Intake Valves used on the 57 and later Engines. Heads are ECZ-C Heads. Actually pretty clean. I don't know if the Exhaust Valve Seats were done with Inserts Yet. I don't have a compressor to take One valve apart and check. There is minimal Ridge in the Cylinders. I have been picking up Parts for the last while anticipating doing rebuild including a full Set of New Valves including the bigger Intake Valves. The Block is 1956 based on date Code and uses the 3 different lengths of Head Bolts. What are the Heads? ECZ-C application. Obviously Someone has worked on this Motor in the Past but not the Bottom end. I am just doing a stock rebuild using a Overhaul Kit sold on Ebay. Quality Parts as I used One about 10 Years ago on my last rebuild.