I'm currently looking into buying a set of the MAC whitefaces myself and am starting to ponder if it would actually be a good idea to put them on.
I visited the MAC website and they have an FAQ on their site. The biggest question/problem I'm finding when I search on the topic of these things is that they don't lite up well during the night. During the day they look great, but at night, apparently they are either blurry, the number's don't show up too well, or to dark. Also, it would be wise to paint the needles red as the orange doesn't come up at all during night driving. Also, before applying the new MAC's on, the surface should be cleaned with mild soapy water as the old dirt and film prevents the light from showing through the new faces.
I called a Mustang pro who's installed plenty of the MAC's and he said first off, they are a pain to install on the foxbody Mustangs because of all the screws and trim and parts of the dash you need to take apart to get to the speedo. Then the speedo itself is a pain to unscrew. He told me he doesn't carry the MAC's anymore because too many people complained about the night lighting on these things. I asked what his labour charge would be on installation for me and he said $120 as it would take roughly 2 hours and the patience to take it all apart and then reinstall.
Interestingly enough, he said the MAC's look better on the 94's and up and the installation is so much easier that to install on a 94 would only cost $60 for one hour of labour!!!!!!!!!!!!!!!!!!!
Lastly, my Mustang Pro told me he only carries the APC Indiglow whiteface guages now as those come with a special lighting system that is installed into your electrical system that lights up the cluster, hence making it more readable, however, he wanted something like $170 Canadian for it!
I just wanted to chime in and give you some idea of what I've found out so that you can make a better decision.
I looked at the ebay whitefaces you showed. I think those may be adhesives as the guy states you don't need to remove the needles. I think the MAC's are actually panels where you have to unscrew and remove the old stock panel and then screw in the new whitefaces. The ones on ebay look like all you do is just peel off the new whiteface guage, slip it over the needles and just stick them to the stock guages. If that is how they work, buddy, at night you won't see a thing on your gauge pod
I'm sure they'll look good during the day though.
Good luck