I would recommend the following book about the development of
the Oxford English Dictionary as something to consider:

  Simon Winchester, _The Meaning of Everything_,
  Oxford University Press, 2003.

This is a fascinating account of the development of the OED
from its proposal in 1869 to its completion in 1928 -- a period
of 59 years.  The time from the first publication of the first
fascicle in 1882 to the final fascicle in 1928 was 46 years.

That time period should be compared to the 19 years for the
development of Cyc, which is very far from satisfying anybody
who is looking for an ontology that could be considered worthy
of being a "standard".

I do not see any reason for assuming that the deveopment of a
good SUO would take much less time than the development of the OED.

John Sowa