Just for fairness I will also mention Tony's book.
The Concise Caves of North Wales by Tony Oldham.
I haven't got it myself but it does list over 250 caves with NGR's.
If it is in a similar form to the Concise Caves of Devon then it will contain some useful stuff.
It is, I believe, available from Tony (rhychydwr1 on here) on a CD and quite cheap...