i'm using a heidts for a nova in my 69 rambler.
checked it to tci's crossmember for a nova and it was too narrow (would have made headers more of a problem than they are now)
i have a heidts in my 48 chevy coupe that i've beat on for years.
i've installed a couple of street rod engineering kits, well, i just leave it at that...
done a few other brands, too but i doubt they'd apply to your 'stang.
not familiar with your suggestion, got a link to 'em?