67 GTO engine
 

I would like an opinion of the value of this engine in this condition. It is
a 1967 GTO 400 CI engine. Block casting number 9786133, date code
E157. Heads are 670 with a date code of A137. Cylinder bore is stock
size.

I am still buying STD bore 400's in that general condition for $500-700. BUT they are generally Catalina or other big car coded blocks. A coded GTO block for someone restoring a 67 GTO may be worth double? Just have to find that person who puts lots of extra value on number stamps. A 67 400 block is a good one for a performance build. Thick, heavy casting.

You need to identify the block code stamped on the front.
Such as WS .... YZ ..... XP .... etc
That alone makes big differences

Also reconfirm the casting dates you listed on block and heads , that is a huge gap between the dates you listed. And wouldn't be considered "matched" in a higher value perspective.

If you have all the ancillary pieces to complete the engine that will raise the value too.

It's a WT block with 606381 above the letters.

1200 - 1500
Disassemble the heads and short block - and have them cleaned and verified at a machine shop as rebuildable. Higher level of buyer confidence and better selling price.

It gives a weird appearance with a couple valves removed and a couple pistons removed. fwiw

Yes, some valves have been removed as well as two pistons and connecting rods.
I was figuring starting at $1500 and go from there.