Hi Wendy
An excellent starting point for research into surname Guihan and its variant spellings is by conducting a surname search on Irish Ancestors website at
https://www.johngrenham.com/surnames as the ‘Surname Search’ option enables you to examine the location, frequency and history of Irish surnames.
Edward MacLysaght in
The Surnames of Ireland records the following information:
(O) Guihan, Guihe(e)n. Derived from Gaelic
O Gaoithin (
gaoth, wind). The name of this Roscommon sept is also anglicized Geehan. Either a branch of this, or a distinct sept, is established in County Kerry: there were a number of families of the name on Blasket Island.
You should also take a look at 'My Kerry Ancestors' website at
https://mykerryancestors.com/