Ive just had a pair Of Ghissallo rims built up for my Mercian fixed. They are
made of Beech, (the old Constrictor were maple made by the Franco American
Rim Co.). My late father told me they used felt brake blocks or very soft pure
rubber, it might be worth trying the blocks made for carbon fibre if you can
get them to fit your brakes. The rims do give a very smooth ride over roughish
tarmac but you should avoid potholes, the big disadvantage is that wood doesn't
bend, it shatters. A good grade of exterior varnish is alright when the
factory varnish wears off.