The Vespin is a very good replacement toilet.
Most people start with one in the house, and when they see how much they like it, order two more.
Since it is skirted, the water supply should be far enough to the left to clear the base of the toilet.
If the water supply is on the wall, then clearance would be at least 7" center to center.
If coming from the floor, a little more to the left.
Your water supply location leaves plenty of room.
We replace hundreds of old toilets every year.
The Vespin comes standard to fit a 12" rough installation and will work at 11.25"
You also have the ability to use the 10" or 14" Unifit kit if you have an unusual situation.
Most of the other Toto toilets are standard 12" rough in installations that fit easily into existing bathrooms.
The water supply on the wall can be 3-1/2" to the left of center on the wall.
They are pretty much drop and go as far as installation goes.