Hi Ian – if you look at the plans, the long section with the sink shown is only 17″ deep, so no go there, unless you widen that section by about 8 inches.
If you place it in that shorter counter on the keg box side, which is 21″ deep, you only need to extend the counter an inch…but need to add about 3 more inches for the usable space to account for the two framing 2×4’s. Does that make sense?
In short, to fit a 22″ wide (deep) sink, you need a 22″ opening.
Also, are you giving me dimensions of the overall top flange, or the actual sink tub?
That makes a big difference.
Your sink Dimensions…only need to worry about the width dimension.
Sink Length: 27″ (left to right)
Sink Width: 22″ (front to back)
Sink Height: 9-7/16″ (top to bottom)
Long side 17″. You need to extend counter depth to at least 25″.
Short side (keg box) 21″. You need to extend the counter depth to at least 25″.
Bottom line, it’s pretty straightforward.