I understand that these are for the front.  They still sit atop the springs, so the springs have to come out to install them.  I had 1" poly insulators at one time, but they made the front end sit too high, so I swapped in thinner ones.

You can really only lower the front of a Mustang one of two ways: shorter springs or drop the UCAs.  Beyond that its being done with torches and welders, and anything like that would be pretty obvious. 

Restoring Camaros and Mustangs is not the same thing.  For one thing the front suspensions are totally different.  When I was a teenager a family friend who restored Covettes and high end Chevys for a living would actually ask my advice when contemplating buying a rare Ford.  His restorations on the bow tie products were nicer than the cars had left the factory.  I would lick the undercarriage of any of the ones on his showroom without hesitation.  But he didn't have the knowledge on the blue ovals.  I on the other hand  had been going to car shows, reading magazines, and books on the subject since I was 10.  Having an eidetic memory the amount of knowledge I retain is crazy.  He'd go look at say a barn find GT500 and then come back asking about what was correct, what proved it was a Shelby, etc.  He was plenty smart and capable, but was also smart enough to know what he didn't know.

In my experience most resto shops specialize in one brand or another.  That doesn't mean they necessarily pass on a car of a different brand if they think there's money to be made, but you can't realistically expect a car of a brand different to what they usually restore to be of the same level.