I remember Maine Hardware being there (the Post Office Station A at the time was in the Libby Building, and when that was torn down for the museum they moved to that spot and Maine Hardware moved to the then-Portland Shopping Center after Arlan's had closed), but I have no recollection of Greyhound being at that spot (and only a very dim memory of it being at High & Spring).
Cathay Garden survived well into the 80's I believe, as did State Drug. A personal Holy Grail would be to find a pic of 630 Congress (currently Mi Sen, the place with the big arched windows) when it was a Howard Johnson's.
I wish Portland had held onto more distinctive storefront signage, whether Art Deco or neon. The one I remember best was the Rogers Jewelers awning near what is now Nosh.