It was one of the youngest finals for many years, between the two schoolboys, with McCall (17) from Gore High School and Croudis (16) from Otago Boys High School.
Top qualifier Liam Balneaves (Greenacres) won the senior plate after his first-round exit, while Mark Brooks (Queenstown) took the senior consolation after missing the cut by a single shot.
Michael Ormandy (North Otago) became the senior B champion but not without a struggle, beating Brandon Hodgson (Otago) on the fifth play-off hole in the final.
Mark Cooney (Otago) also went to a play-off to take the intermediate title, while Kayne Wardell (14) put the small Allan Grange Club on the map by winning the junior event.
Croudis took the early lead in the senior final when McCall went through the second green.
On the fourth, fifth and sixth holes, McCall had three shocking lies but still managed to square the match when Croudis made a tactical error by attacking the pin on the par 4 fifth.
McCall took the lead with a birdie two on the seventh and pitched close for another birdie on the next hole, to lead by two.
Croudis reduced the margin to one when McCall finished through the green at the ninth and the pair halved the next three holes.
But McCall birdied Tipperary after being on for two and won the next two holes with pars to finish the match.
McCall gave Michael Minty (St Clair) little chance in their semifinal, when he scored a 68 to win in 13 holes.
Croudis trailed Otago team captain Andrew Hobbs (St Clair) by three after six holes but reduced this to two with eight holes to play.
Hobbs bogeyed the next four holes, putting Croudis two ahead and the match finished on the 16th green.
