ID THIS BLOCK

Thank you both for the responses.
Not so much interested in what it came out of as the year of manufacture.
The pic is hard to see because it was double stamped. As a '79 year, if I understand correctly, the vibration damper is different (cast crank vs forged). Other than that most everything else in interchangeable.
The motor is a replacement for a '67 Dart.
The top of the deck is stamped .030 and the pistons are .030 oversize. is that a manufacturing stamp or did the machine shop do that.
To finish the story of the acquisition, the machine work was performed in 2016 but the owner died before finishing the project. I bought it from a relative who was willed the motor/parts. Unfortunately, no paperwork is present to verify what was done.
My plans are to take it to my machinist have the work verified.
Is there any advantage/disadvantage using the newer head as opposed to the '67 casting? I kinda like the 'drool tubes' as they are unique to the slant six, but if the newer head is ready to go with hardened seats, I would be foolish not to use it.
Also, as this is a cast crank with a smaller bearing surface, should I look for fully grooved bearings for better oiling?
For my own education, how did you decipher the build (cast) date?

Thanks for your time
'64 Dart
Whether it's a '79 or '89, any Slanty built '68 & up has the larger converter nose pocket, contact Member @slant six for the reducing ring to install in the crank. As far as fully grooved mains, unless it's going to be really hot, totally unnecessary.
Deciphering is sprinkled sporadically all through this site & this forum in particular, but slantsix.org, or aquire Doug Dutra's SA book on the Slant Six has the info. There was a great Valiant/Barracuda site that had lots of info, but I haven't tried looking them up in a while, I have printed out things from there a while ago....sometime around 2016 or so.