What it is?...

Well, I got under the car today.. The block is casting 2780930-340-6 dated 5-31-72... Low compression 8.5:1 or high of 10.2:1 ?.. Most likely a forged crank... The heads are maybe J 3418915 (can't confirm) with LPS 7278 punched in above block ID (which I can't make out with the pitting)... The valve IN size, 1.88 or 2.02, maybe 1.88 if made in 5-72?.. The 4 speed 833 was cast in 7-23-76... The rear pumpkin is casting 1820657 and is 1958-64 non posi, gears unknown... Any suggestions as to valves or compression?..