Any stellar performances of Irish music...

OMG, Sinead, Haley, Celtic Women? Any true Irishman would throw himself on a spit of hot coals rather than listen to that. No more need be said of that ilk.

Go to Topic records website, go to the link for the radio program "Thistle and Shamrock" and easily educate yourself on true Irish singers.
Sinead is on vinyl,btw...only most of the early Sinead is probably not what you're looking for.
Good luck!

Mary Black
Maura O'Connell
Delores Keane
Mary Coughlan

Look for anything with sisters Triona and Maighread Ni Dhomhniall.

They were together on the rare Skara Brae record from around 1970; Triona recorded with the Bothy Band and Relativity and later solo; and the sisters more recently have again recorded together.

Also Karen Matheson in Capercaillie. My preference is for the first 3 albums, before they added a drumkit and spoiled their sound.

I have no idea as to availability on vinyl. This isn't material about which you can afford to be too picky.

Forgot to add, look for the Shanachie label as well, they had quite a few lp pressings out there. Audiofeil has a nice list for you.