You can trim any of those back as much as you need. They'll look bad for a while, but one good trim ought to do it. Then of course a trim once or twice a year to keep them in check.

Here's my advice. Trim them back harder then you want to. If you only trim the boxwood back to 1.5 feet, then every-time you do your touch-up sheering, you'll be
exposing all of those bare, scraggly branches. So, prune them back an extra 6 inches to allow new leaves to flush out to the size you want, then the annual trimming will look much more appealing. Does that make sense? I hope so.

One more, when you choose to do your trimming, try and get a week with over-cast weather. Those unexposed leaves and branches will scorch in the bright light. The over-cast will give them some time to adjust.

The Holly and the yew, you could hack them to the ground! They'll come back (the yew will be slow). And, if you hold of until the holidays, you can use the holly for decorations.

Sometimes, somethings just don't come back (specifically the boxwood). But, if it's the wrong size, it couldn't hurt to try. Boxwood is cheap, you can always replace it if you don't like the results.

Thanks so much for the answer. I have already begun cutting (severely, as you mentioned) the north sides of all the hedges. Then I have started to thin the tops (reaching way down inside and cutting to the tiniest green leaves. In the spring I will take down the tops and south sides. I think this will work well. I will follow your advice with the Holly & Yew @ Christmas. Again, thanks for the advice, I was beginning to wonder if anyone else reads this site!

Yup, this forum is S-L-O-W. But I love the concept and hope more people post. Good luck on your restoration, I hope it comes out perfect.