Rootlieb probably sells the best reproduction aprons as I believe they have the indentations on the front part where the front fender attaches and the area where the rear fender is attached. Unless Howell's has changed, they don't make a splash apron with the indentations. I will never purchase anything from Howell's again. I think their items are not made very well. If it were me, I would try to purchase a decent original apron and restore it. They are readily available.
Rusty Nelson