26" balloon tyres

I've almost completed a renovation of a French 50's randoneer bike but have had some difficulty trying to track down vintage tyres to finish it off. The ones I need are 26"/590mm size, which is actually slightly larger than the tyres which I believe most of these older randoneers were fitted with, seeing that I found that I couldn't restore my example's original wheels and had to plump for standard 26" sized replacement ones instead. In tracking down parts, I did manage to find a pair of the older sized 650B/584mm tyres (before I bought the above 26" wheels), so would be happy to trade these for tyres of the other size.
They would really need to be vintage tyres (or modern ones without flashy labels etc) and preferably all white to match the originals, or at least whitewall. And I believe that, if the tyres are Michelin/French made ones, that they class the 'baloon' type of tyre width as either confort or semi-confort, so I'd be happy with either of these.

Thanks in advance.

I'd also consider a pair of the above mentioned 650B/584mm sized wheels, since I'd then be able to use the tyres of this size I have.