As for the genuine ones, there's a small chance of finding NOS on the auction site. However, looking at the Velobase photos, these chainrings look pretty much the same as the ones used on other 105 or 600 cranksets from the mid-late 80's. These were 6/7/8 speed groups in the 80's. Which should be more or less compatible with the Golden Arrow mechs. If your rear derailleur is Golden Arrow, that's friction only, so even less of a headache, it would probably be difficult to find something that doesn't work. If you're adamant you want to stick to Shimano chainrings, these can be found from time to time in new condition. In the mean time, you could look for Stronglight chainrings, which are decent quality anyway. If in doubt, I'd take Vernier calliper, check the thickness of your current chainring teeth etc. and ask the seller about clarification on their product.