I use clipless on all my vintage bikes. Toe clips, straps and cleats? Been there done that, not going back except for Eroica, damn. The only issue is if the crank had French threads, then modern 9/16 threaded pedals are a no/go. I just converted my '78 Peugeot to clipless SPD, by changing the Stronglight crank to a Sugino. All good now. Actually the Stronglight TS had stripped pedal threads when I got it, so changing it was a nobrainer.