First in Quality and Strength is Fat Man Fabrications. Contact Brent (owner) with your inquiry. If he doesn't have it, he may do one for you anyway. Years ago I sent him drawings of my 1936 Hupmobile frame and he did his first ever kit for the Hupp. When I got his kit, it was a perfect fit and simple to install. I think it was 6 inches wider than normal but fit like a glove. Still working great today.

There may be a reason not to put a Mustang II on some cars, so call and talk to Fat Man about that. They will only do one if it is an improvement.

Good Luck with your project.