I saw this and thought of you and your Mustang project. Damn, lost it. It was a Ford group on Facebook showing factory spring tower mods for the Boss engines. I'll see if I can find it. Sorry for the false alarm.
BLUE OVAL MUSCLE CARS & COLLECTIBLES | Facebook
The first is a Mustang with factory towers for the Boss. The second is a mod to a Falcon and the 3rd is to a 70 Mustang using Fox Body towers for a 4.6 DOHC. Those photos were found by clicking on the first photo and finding them in the comments.
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