The V= 8 cyl. engine
C = Bel Air
S = asembled in StLouis
105753 = production sequence number.Car assembled in March of 1956.
Engine number
0600144 = 601144th engine built , F = at Flint plant, 56 year of engine, last F = Corvette engine with 3 speed transmission.I think you will find there should/will be another letter after the last F.The 1956 passenger car 265 engines were FB, FC,FD and FG plus some had a G prefix.
There is no way to tell if its the original engine.
The Fisher body tag on the firewall would list the body number, paint number, trim (interior) number and body style.The paint number for Plum and Ivory would be 708.If I remember correctly that color came with a Charcoal and Ivory interior.
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Chevgene