Thanks !
I ordered it from Moto-Lita, very friendly and professional staff.
The specs are :
14”, 4 Spoke Black anodised Morgan wheel, slotted spokes, flat, black leather rim with thumb grips.
It's custom made indeed. I was looking for something a bit more sophisticated than original and four spokes like many cars from the 30's.
I am quite happy with it, now I need to wait to install it, my car is in Morgan France, for service.