Joshua S - you got it correct. It's a Model 149. I'm not sure of the chart you were looking at but your tractor serial number 2050047U420043 breaks down as follows:
205 is what IH called the Kind Code (or what I call the Product code) identifying it as a Garden Tractor (so it's an IH Cub Cadet)
0047 is what IH called the Machine Code which identifies it as a Model 149.
U is for Made in the U.S.A.
420043 is the serial number indicating it was built during the month of Feb. 1972.
Now, you should have a 14hp Kohler Model K321A engine but the serial number doesn't provide any ID info that I'm aware of, and since the Model and Spec numbers are scratched/worn off the tag you'll have to do some investigating. If you can possibly see any of the Spec No. the first two digits for a 14hp are 60 (for a 12hp it's 47 and for a 16hp it's 71) . Sometimes if you get the light just right you can still see at least some of the Spec numbers since they were pressed into the tag. Otherwise you'll probably have to pull the head and measure your cylinder bore. Sounds like you have some reference material but just in case, the cylinder bore for a 14hp K321 is 3.5", for a 16hp K341 it's 3.75", and for a 12hp K301 it's 3.375".
(Oops, Mr. Plow - yes a hydraulic lift was standard on a 149 but there are many 129's, 169's, and even some 109's with it, like Jerry's Nines Are Wild has in his profile).