If you are talking of the 1970's, the days of the 42 tooth ring being the smallest (except for the fabled and seldom seen 41s), the BCD was 144. Still is on many track cranksets like the Sugino 75.

I'd google Sugino, 144 BCD and 3/32". I think you can just turn outside rings around and use them on the inside (but I haven't tried it). Seems to me I would have heard it wasn't possible in my days when the 52-42 crankset was the gold standard and I was hanging out with some very innovative mechanics, one of whom has since achieved some fame as the man to go to with questions like this. Sadly, he passed a couple of years back.

Ben