Source of replacement antique wood siding?
My house was built circa 1850-1870 in the humid climate of middle TN. The original weatherboard siding appears to be made of yellow poplar. It is of uniform 7/16" thickness, and each board is about 6 1/2" wide, with enough overlap to leave about 5" of exposed board.
Some of the original siding planks are in such bad condition they need replacing - splits in the board, rotted ends and rot around the nail holes. I have repaired many of the boards over the years using epoxy filler, but some boards are just beyond repair.
I cannot find a source of wood siding that comes anywhere close to the dimensions of the original. I have considered replacing the rotted pieces with cedar instead of poplar, but the only cedar siding (or for that matter any species of wood) I can find is wedge-shaped instead of uniform thickness. The wedge shaped stuff (also available in pine) would be OK if I replaced all the original siding, but it won't work as a replacement for the rotted planks, mixed in with the original.
Any suggestions where I could find something identical or similar to the original, or how I could go about having some custom sawed? The local sawmills only do rough-cut oak and poplar for barns and farm buildings.
I don't want to replace all the siding, since only about 10% of the original planks are damaged beyond repair.