Cast a Wider Net?

Since William McCown of York Co., South Carolina is shown as McCown in the
1790 census, as McCoun in the 1800 census and as McQuown in the 1810 census,
it seems as though I will either have to look for his descendants as McCown, McCoun or McQuown.

Meanwhile census reports in my own line show the name as McCown, McCowen
and McKeown.  I can either search all of the above spellings or simply look for McCown and it's spelling variants.  So far, sentiment seems to be to simply look for McCown.