Not sure what to recommend. I just did a fast search and saw the suggestion to try to go from unigraphics to IGES.
Look into a program called polytrans from okino. It may have a unigraphics to maya translator.
If there is no direct way to go from unigraphics (whatever that format is) to maya you will need to get the data into some intermediate format that maya can digest unless you want to write your own translator.
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675