The closest I got were three 1960s patterns, but none of them seem to be slim fitting. I prefer the slim fit because it looks better on a slim man (now that I'm half the man I used to be - well, maybe 75%). We all need to use clothes to show us in our best light, don't we? The ladies certainly do (not so much these days, of course). In the U.S. two years ago it was really easy to find vintage shirts and suits, but they were all huge. Americans eat a lot more than Aussies, it seems. I'm currently wearing one of my thrift shop bargains though. An Italian suit, probably '90s but it doesn't matter when it fits this well. Classic design, with pin stripes, and very slim fit. The price? Same as a good op shop here: $10. Can't promise to ever learn to make suits, since it would take many years to make something even acceptable, but shirts are a different matter.
I hereby promise to attempt to create and publish an electronic pattern from the paper one I made my shirt from. Here are two pictures of it as it is now - I have yet to sew button holes on:
Etsy seems to be the best place to find vintage patterns. The three I found earlier today are simplicity 4160, simplicity 7745 and butterick 5897. Just remember that pattern numbers are re-used so include 1960s in your search. I'll figure out some time how to digitise the pattern I have.