I have checked my Bangkok visits and see that my first Apollo experience was 1980. I can say definitely that by then the little bar was on the left of the entrance. I remember because I spent many visits over 2 or 3 years perched on a bar stool as I had a thing for the student bartender. Sadly he did not have a thing for me, but it was still lovely chatting to him and then turning to watch the boys strut their stuff on the catwalk, especially when underwear came off and at the boys were in their birthday suits.
So I expect it had been remodelled. It certainly had an upstairs with one or more short time rooms, But the ground floor was occupied by another tenant. I never attended any other bar on that soi which may be one reason it seems to be etched on my memory!!