Is 1/2" leaf spring relocation worth the trouble?
Take a look at Forgestar. They have 2 stock designs that are offered in sizes that will work on my car. They can also do custom backspace.
I just completed my set of (4) 18x9 Forgestar F14's, bought the last 2 off American Muscles website. Just checked and they don't show the ones I bought anymore. They still show them on the Forgestar website though.
https://www.forgestar.com/wheels/f14?variant=230715
But AM does show an F14C in 18x9.5 that might work.
https://www.americanmuscle.com/forg...ave-satin-black-wheel-18x95-f16289565p35.html
An area of concern on the 18x9.5 wheel is could the wheel contact the UCA at full lock and the suspension at full droop. If that were to happen on the road, things would be going all kinds of wrong, but I wouldn't run a wheel that could do that. The fix for that might be tubular UCA's.
One thing to be aware of with the Forgestars is that if you buy them from AM, they have a Mustang center bore size which doesn't match the spec on Forgestar's website. Guessing they are custom machined for AM. Only trips you up if buy them from AM, don't run a Mustang spec wheel bore size on your hubs and expect them to fit without machining.
One nice thing for me was that because I machined my front hubs to fit Mustang wheels mine bolted up without any work, including opening up the wheel hub beyond the locating bore. Some wheels (like Enkei RPF1's) have to be bored out so the center caps don't work, but these didn't need that. And Forgestar sell a raised center cap that might even work, but not certain.