Okay, I've been able to score a copy of the Rotterdam (Heller), Houston (Revell), and Franjirk (Revell) and they are all different kits/molds, all three in 1/200 scale.
As stated the above, the Rotterdam is the largest, then the Houston, then the Franjirk (I know I'm not spelling it right but I'm too lazy to go look.) Anyway, the Houston kit appears to be close in size beam wise, but is about an 1 - 1 1/2 inches shorter in overall hull length. Also, the Houston is a one piece hull compared to the Rotterdam which is two pieces, and while both have similiar designs, the hulls are shaped differently. I haven't looked too hard at the superstructures yet.
The Franjirk is about 1/4 the size of the other two, however it is a habor tug and not a seagoing "wessel," as Ensign Chekov would say. It also has a one piece hull.
Wilbur: Be interesting to see pics of your build should you get a chance.