WHAT IS THE YEAR AND WHAT WAS THE ORIGINAL SIZE OF THIS CHEVY?

Hi Guys, this is my first post and Im wondering if someone would be able to help me with identifying a Chevy engine I was given many years ago. I think its been stroked to 383? from originally a 350?? What Year is the engine? I think maybe a 69? What does the S Cast letter indicate? Im guessing short Why are the 010 numbers on both sides of the block? The letters I can make out on the right front pad are Possibly U I T T (T on top and bottom lines) K L. Numbers - 509861 with a 1 also on the top line? Was the harmonic balancer specific to and Cci? Ha anyone seen the Block casting number facing the GM cast letters? I have attached a photo with the ROUGH measurement using a plastic set of verniers indicating the stroke. Im guessing its 350 stroked to 383? There are two different number Pistons? They are dome top forged pistons? The appears to be a D stamped near the Oil filter? I look forward to your reply and Knowledge base as Ive never had to try an ID such a mess before and Its left me scratching my head. I would like to build it up to put in a 72 HQ 08 four speed Kingswood ute which currently has a VJ prefix 304?. I have also attached a photo of the VJ prefix and numbers on my current engine and would also like some assistance in pin pointing its origin as the VJ prefix appears to be a bit of a grey area. Cheers Guys and thx in advance. Daniel