I'm looking for some pictures of the effigy dated to 1502 in Ardchattan Priory showing the supposed earliest form of

a scottish dirk, my search on internet has been fruitless, thanks for help

Do you know the name of the person in the effigy?
If you do, you can do a search here:
http://effigiesandbrasses.com/

Unlikely. Clan Chattan was not of the social order to be setting up funerary effigies.

Best bet would be to track down some of the local antiquarian journals to find any tidbits on funerary monuments. Most of them are surprisingly intact as central and northern Scotland were not bombed during WWII nor badly affected by the great vandalism of the English monastic suppression of the 16th C. Its just that so many funerary monuments were made from crap local limestone and so have not survived the centuries.