1977 Tour of Ireland included a stage to Kenmare and a stage around Kenmare, Ángel Arroyo won the GC. He was later 2nd in the Tour de France in 1983, and is the guy whose positive test gave Lejarreta the 1982 Vuelta win.
In the 1976 edition, the Kenmare stage was won by Francisco Javier Cedena, who later won a Vuelta stage in 1981. Juan José Moral, who also won a stage that year, won a stage of the Peace Race but never amounted to much as a pro. Other stages were won by other prospects who either fizzled out or only became domestiques like Luís Miguel Ortíz, Luís Enfedaque and António Abad. Miguel Gutiérrez Mayor, who was Arroyo's right hand man in 1977, later did the Tour and became a fairly established domestique for Teka for a few years. Unfortunately can't trace to find out if any of the domestiques may have been any future stars - the era we'd be talking means you'd be looking out for riders like Alberto Fernández, Pedro Muñoz, Marino Lejarreta, Faustino Rupérez - it's a bit too soon for the likes of Pedro Delgado or José Luís Laguía.