If I can say Im not sure about the tyres, amber walled would have been better - but thats just me!
I would guess that the tyres are probably 27 x 1 1/8 and if so the conti's are about all that is available. I really wish that Michelin would do a batch of world tours in that size as the Conti's really don't look right on 80's bikes. I'm having the same problem with my Raleigh Royal. My 27 x 1 1/8 Michelins have finally ended their life and the 1 1/4 I have put in are really too large, I can't actually inflate them as hard as I would like because they rub on the frame. At that time Raleigh did a lot of their bikes with close tolerances for 27 x 1 1/8, I guess all the other makers did too. My Royal originally had Michelin Club Tourist tyres on but since then I have used nothing but World Tours. Sadly, I have just ordered a pair of Contis for it. My wifes Carlton Courette is even tighter tolerance and the 1 1/4 world tours are unuseable unless I take the mudguards off.
If anyone from Michelin reads this PLEASE do a run of 27 X 1 1/8. There must be 1000's of 80's bikes in desperate need of them!
Think the Wisp looks great by the way but if it was mine I would put the mudguards back on.