I acquired a 56 F100 frame with a Y block engine. Decoding the frame VIN it indicates the truck was equipped with a 272. 2V. The engine block is cast with EBY (256) the heads are cast with ECZ (272). Pulled the distributor and it has 14 tooth gear and hex drive. Is this a 272 engine that possibly cam with truck or down the line did someone put 272 heads on a 256 block. What else can I do ie drop oil pan, pull cylinder head to help verify what I have?