Don, if he can produce/manufacture ANY wooden waggon wheels in 1/35 scale, then a blind man would be glad just to see the spokes, whether they be square, rectangular or oval shaped.
If he can ' pull off ' making a wheel in 1/35 scale, that even looks remotely like it has a hub, fourteen spokes and seven fellies. then add a steel tyre to it, I don't think "you" will even notice what the spokes are shaped like. Actually, a toothpick would be about the size required for the spokes for this Herculean effort.
Good luck to the person in question who is attempting to make these wheels and if you are reading this, then please keep everybody posted on your progress.
If you have not allready read this page, then I suggest you do, particularly the sections on anything to do with making wheels.
http://www.scalemodelhorsedrawnvehicle.co.uk/(Tips%20&%20Ideas).htm
If you want to take the " easy way out ", then this site posted below, might just tweek your interest.
http://www.wildhorsebooks.com/ModelWheels.htm