I would suggest not getting too hung up on Litríocht for pre-Caighdeán books -- a better source would be
http://www.abebooks.com, a worldwide association of used book sellers.
When you search ABEbooks, remember that many sellers don't know what the dot is for, and so will omit it from the spelling of titles, names, etc. And most won't bother with fadas, either.
I echo Liz's recommendation of John Lenihan, but use ABEbooks to check how much of a bargain you're getting with John. His auctions are very popular, and can get a bit pricey. His descriptions make good reading, whether you're bidding or not. He really does his homework!