I don't know that you have to stick to Japanese frames ... a lot of the British lightweights of that era were sold as framesets only, and while you certainly see most of them built up with Nuovo Record or Super Record, you also see quite a few with Shimano 600, Shimano Golden Arrow, early Dura-Ace, and Superbe. While it's not period correct, I've got a pristine Shimano 600 Arabesque group which I'm going to use on a '70's Bob Jackson which I'm restoring. I think it'll look just fine, thank you, and should work pretty well, too.