SO... sorry to bump this old thread, but I finally decided to do some research.. anyway I think I FINALLY figured out what I have here..

According to my muscle car friend and the internet this is what is referred to as a “Counter Exchange” or “Warranty Block” more commonly called a “CE” block. the number on the crate was missing a 6 in the middle because of the strap used to hold the crate closed.. the actual number is 3966921, which apparently was essentially an over the counter "short block" or "partial" 1969 LT1 engine..

It apparently can come in different configurations.. This block is the complete lower end, and is the correct, direct LT1 warranty replacement for a 1970 350 4 Bolt Main application for a 1970 Camaro Z28, Corvette LT1 or Yenko Deuce. It is 11:1 Compression Ratio.

All of the parts are correct for the 370 HP LT1 Hi Performance 350 4 bolt main replacement motor for the above applications.

This motor is dated “H” (I don't know how to read these date codes). It is a correct and direct warranty replacement motor for any 1970 dated LT1 car.

Suffix: CEB1330
Casting: 25 GM 3970010

Date: H 38 0

Pistons: 3959456 (TRW impact extruded pistons, 11:1cr)

Crank: 330550 (forged steel crank)

Cam: 3972182 or 3972178 (cant see the cam number)

Main Caps: 3861 GM 348

LT1 "pink" rods, forged steel, shot peened, high RPM rod bolts

Now that I KIND of know what this engine actually is I'm sort of excited and don't want to give it up, but does anyone know what its actually worth? It needs a good cleaning from sitting in my families garage for 45 years haha but its BRAND new! I was told by someone that these original forged GM crankshafts are VERY hard to come by and might be worth several thousand by itself.. any new info greatly appreciated!