This is what they look like to me and my brother inlaw. heads 3870126 or 8970126 Motor looks like 3914638 18t219143 t0325dh had to repost numbers some were missing motor came with 67 camaro just throw in car was not running has a deep old stlye weilded oil pan on it have not looked inside yet.

1967-70 3970126 327 1.94 1.5 Heads

1968-69 3914638 327 - Block


Your heads are 67, i think the block is 68, i hope this helps

River

Partial VIN indicates a 1968 Full Size Chevrolet Passenger(18TXXXXX)
The Suffix (DH) indicates a 1968 307 Towanda engine from a Full Size with a PowerGlide trans.
Block Casting Number is most likely 3914636

3970126 Heads weren't available until the 1969 model year (some listings are incorrect...) so they were probably swapped at some point.
These heads were used from 1969 to 1972 in Passenger applications and an additional 2 years (1974) in light Truck applications. Most are of the small 1.71/1.50 Valve size and had very small port sizes - not to good for performance use...
If the Spark Plugs are 13/16" then the heads are pre-1971 model use, if they are 5/8" then they are 1971 or later.
Larger valved heads wouldn't make much sense on a small bore 307 engine anyway...

Hope this helps;
John