A few 747-200s were reconfigured to have the same upper deck as the 300. KLM and UTA did the conversion to a few of their airplanes. Initially, the 747-300 was going to be called 747-200SUD... but Boeing changed the designation to 300. Swissair was the first customer for the 300... No USA air carriers operated 747-300s...
There are not many differences between a 200 and a 300 (there are differences which came from different options offered by Boeing, but were available to any 200 or 300 when ordered).
Therefore, the 747-206SUD has the same upper deck doors as a 747-306.
Hoping this does it for you...