Edit; I have 10 more sets ready.
These plates cover the holes for the J tubes in the top cylinder tins when the heat system has been deleted. Leaving the holes open allows the engine to suck hot air from below the tin.
The set consists of two plates and mounting hardware. The plates are mild steel and powder coated satin black.
I now include a speed nut with screws and washers for easier installation. The speed nut clips to the inside of the J tube hole.
Price is $30 for a set including shipping in the U.S.