Possibilities for replacing old wall hung toilet?

We bought a house that has 2 bathrooms with wall hung toilets. The house was built in 1965 and I'm not sure if they were from that time, although I wouldn't be surprised if they were.
Anyway, we are remodeling one of the bathrooms (gutted to the studs) and only replacing the toilet in the other one.

If I don't want to do much additional plumbing work, are my only options to go with either the American Standard Glenwall, Crane Rexmont or Gerber Maxwell Wall Hung?

If I had it my way, I'd install floor mount models (I just like the way they look better and are also less expensive), but it seems like a lot of plumbing work to adapt the bathroom to a floor mount toilet.

I don't want to keep the toilets there now because they are an ugly brown color and I want white.

What would be the least expensive option to my problem?

Any help appreciated. (Obviously, I am not a plumber)

For 1965 wall hung replacements, I like to use the American Standard Glenwall and the Gerber Maxwell Wall Hung,

Edited 1/16/2014

Click to expand...

I sell quite a few, they work well and they look nice.

I wouldn't bother with the other two mentioned.

No matter what you do adjusting carrier to fit new toilet is probaly not
posible glenwalls are OK installed a few. You may need a new carrier to
accomadate any wall hung W/C.

pic added - do I have a carrier?

Thanks for the help so far.
Now, just to educate me a little more - I've attached a pic of the stripped out bathroom so you can see the piping.

If I go with the Glenwall, do I still need a new carrier? Or is the carrier for the Glenwall the tank?

Could I install one of the European style wall hung toilets that don't have a tank showing?

You need a 6" deep wall if you want to go with a concealed tank.

If you want to use what you have with the Glenwall you will have to measure.

It looks like in this instance, you'll need an even deeper wall since your vent stack is directly behind where the toilet was - basically, now you have NO available depth in the wall.