Go to ebay motors and look up ebay store "hurst-shifters" He is an independent seller and rebuilder of hurst shifters located in Fort Mill, SC. He is not part of the hurst company. I have bought numerous items from him, and he is helpful, and knowledgeable. You may have to email/"ask an ebay question" to get the phone number.
I do know that almost any Hurst shifter HANDLE that is secured to the shifter mechanism itself with two bolts is interchangeable with any other Hurst handle that bolts on the same way. ( some OEM Mopar Hurst handles were a "slip in" design instead of bolt on)
You can use this to your advantage to utilize a handle that is curved more to the rear or whatever. My 67 coupe is an extreme example of this. I have a Muncie 4 speed, utilizing a hurst shifter and linkage that was for a 69 Camaro. The HANDLE is a pistol grip Mopar design originally intended for a 70 GTX. I just like the look and feel of that pistol grip, and the curvature of the handle brought it back to a comfortable position. ( It comes up through the stock mustang hole in the floor) The Mopar Hurst handle bolts to the Chevy Hurst shifter body as I previously described.
The key points I want to make with this rant are:1) If there is some type of mounting plate available out there that will help, the ebay guy I mentioned is expert, and will know about it. 2) Just changing to a different bolt - on handle may solve your problem, and it doesn't have to be one that was intended for a mustang, or even a ford. He stocks, or can quickly get, any Hurst handles made, and has pictures of many of them on ebay. Remember that the stock ( non hurst) mustang 4 speed handle had a pretty agressive bend towards the rear of the car.
Also, remember that if you move the shifter body itelf very far ( say with a different mounting plate), you will most likely need different (longer) linkage rods. Good luck.