A quick search of the Chip Guide doesn't show many casinos that used this mold. Based on open/close dates, these could have been as recent as the early 1990s.https://www.antiquegamblingchips.com/molddesign_dice.htm
MD-1, first item on the list.
Portland Card Co. is the predecessor to ASM (if memory serves right). Not sure when they were made, short of seeing when others were made on that same mold and making the guess these were around that same time.
Cool chips!! GLWS