Actually you are wrong. In respect to the factory K-member I had the rims pushed out an inch and was running 245/45/17s with lowering springs and they never rubbed. I don't know how that changes with a K-member since they quote these things for 79-95, and I don't believe the
suspension is different from 85 to 87 except the spindles.
What ever!
The four-eye k-frames are shorter - end of discussion. I strongly suggest that check out a real book not not listen to the BS you read in some threads, or by people trying to sell you cr*p.
Amazon.com: The Official Ford Mustang 5.0: Technical Reference & Performance Handbook : 1979 Through 1993: Al Kirschenbaum: Books
Define "don't rub". Yea, on perfect streets and no bumps maybe. But, most people do not live in SoCal with their concrete, pothole-free roads. In the real world, for
most of American drivers, there's a good chance that they will fully compress the
suspension at least once.
For lowering springs, you need 600+ rate springs for a 1/2" drop. Otherwise, your car requires less force to go to full jounce. Add in the POS Stang front
suspension geometry, and you have a car that
handles worse than stock. Again, check out the
Official Ford book I linked to. The Mach1, Bullitt, and 95 Cobra R are all examples of properly designed Stang suspensions for the real world. The 95 Cobra R was designed as a pure circle track handling car (no AC, no radio, sold only to race teams/members, etc).
Feel free to a Mustang car show, find a 100% stock GT 4-eye (stock rims, stock tire size, etc), check out the front wheel clearance to the edge of the fender. If you find one that has over 1" clearance to the fender lip with the original unmodified body-work-free OEM fenders, let me know. We have the Mustangs Unlimited shows here twice a year.
The 1" wheel spacers and lowering springs says it all. You're looking for
looks and not handling or quarter mile time. That's fine, that your choice and your desire.
I help people trying to get better handling from their Stang. And, sometimes, better qtr mile times. For
looks, it's what the person wants. There's not really a better or best option.
Last, do you also realize that there were 2 different 87-93 K-frame designs, the 87-93 K-frames changed some mounting points multiple times, and the strut tower moved multiple times over the years. So, even if you read that someone put an "87-93" stock k-frame in a 4-eye, that's only partially useful info. There are still a number of possibilities. And, even 0.1" clearance one way or another often makes a big deal. So, an aftermarket "87-93" K-frame can not be a 100% exact geometry replacement for all 87-93 K-frames.
Have Fun!