Rustor,
As Kenjo has suggested, Old Maps at:
http://www.old-maps.co.uk/is a good place to search.
If you go to Stewarton, you will quickly find a farm called "Righead" and a "Righead Smithy" just to the WSW of Stewarton.
However, you might find it easier first to search a modern map at:
http://www.multimap.com/If you go to Stewarton, choose a scale of 1:25,000 and move around the map you will find Bloakhillhead (W of Stewarton), Mosside (N of Stewarton) - it seems that both are still farms - Righead Plantation (N of Stewarton) etc.
There is mention of Mosside and Bloak at:
http://www.wcouperthwaite.co.uk/stewart.htmIncidentally, what you saw in the spelling of Mosside was the long 's' - frequently people used a long 's' for the first 's' in a double 'ss'. It was
not an 'f' or a 'p' though it might rather resemble those letters to a modern eye and though it is often rendered in modern transcriptions - erroneously and rather tweely - as an 'f'. The correct transcription of the long 's' is as an 's'.
Good luck,
JAP