:hullo: My grandfather is getting his first tattoo for his 90th birthday. The family (and Grandad) has voted for "living legend" for the script ---- we were hoping we could get an Irish translation of this. He isn't very particular about what dialect. I personally think standard Irish (CO) makes the most sense but doesn't really matter. We will take anything ha ha. Hopefully someone out there can help us with this! Thank you in advance!

I wouldn't think "finscéal" could be used for a person. The dictionary gives "Laoch lena linn féin" (literally, "a hero in his own lifetime") for "living legend". In the 1st person it would be: Laoch le mo linn féin ('a hero in my own lifetime').
It's not a set phrase in Irish though, the way it is in English.