Coupler needed for narrow gauge display

Narrow Gauge Forum Group-

I am looking for a coupler to use on a prop locomotive display for a museum project. The locomotive will be 'generic' and follows no prototype as of yet, but it will be about 6 ft tall and no longer than about 2 feet deep. Basically I get to build a wood pilot, a boiler front and a headlight bracket. I'd like it to look realistic in appearance, and I'm secretly hoping he doen't mind that it resembles a K-27. The client is supplying a vintage round headlight. Because of this 6 ft height, I think a 3/4 size coupler would be ideal for this project.

I live in Los Angeles, and you would think some movie special effects company has already made a fiberglass coupler that I could use for this project, but so far I haven't been able to locate one. A shop that makes movie props quoted me $1500 for making a coupler and a box that mounts to a beam. Seems like there is a better and more cost effective solution for this. Where can I find salvage parts of 3/4 size knuckle coupler and possibly a coupler box that would bolt on to the face of an end beam? Thanks in advance if you have a source for such an item.

Jake Johnson