There's no online resource that I know of, but you'll find lots on the glorious RSSSF.com.
Best one-stop-shop source for results is a book published by the English AFS (Association of Football Statisticians), by Niall or Neil McSweeney, with an imaginative title along the lines of "A record of League of Ireland football 1921-1985". Very comprehensive, but as the name suggests only up to mid-80s. It's hard to find- I have a rather battered photocopy of a photocopy- keep an eye on eBay.
Alternatively, pop down the library and trawl through the papers!
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