I purchased a Wesley Richards shotgun quite a few years ago without a fore-end. I have taken it to quite a few gunsmiths to see if the can make one for me, but without a drawing or photo they were not interested. It is a box lock action (Ansen & Deeley patent number 6955) I would appreciate it if anyone has any information or a picture of a fore-end of a similar shotgun.
Even forearms were individually fitted for each gun. In other words, there is no other fore-end iron on the planet that will fit your gun without significant gunmaker effort. Even on basic guns, they were filed out by hand. Therefore, you can't just give someone dimensions to copy. And it will take a real expert to build one and then fit to a forearm of closely matching wood and execute the same checkering pattern. I would start with JJ Perodeau
http://jjperodeau.com/ in OK. I don't know if he would take on the project, but he would certainly know who perhaps could/would do it. However, it will be a very expensive investment. I would also note that if the gun was an ejector, that complicates things enormously. Another option is to send it to Westley Richards. But unless your box lock is actually a drop lock, I suspect that effort would cost considerably more than the gun is worth.
Trying to restore these old things are acts of love, not economic common sense. I have in my safe a box-lock 20 bore which I purchased for about 1500 dollars. After having Keith Kearcher re-brown the barrels, Turnbull re-case color the action, and a local stock genius restore the stock, I had put another 2200 into it. I suspect with a little luck I could now sell it for around 2500. It is a fine madness.

Give JJ a call. If the gun is in very good shape otherwise, it might justify the expense, and he would at least give you a truly informed opinion about your options. Best of luck.