To help with the confusion, Leven, the town, is on the coast, quite a few miles from Loch Leven. In terms of genealogy searching, Leven is in Scoonie parish or registration district.
http://www.nls.uk/maps/early/os_scotland_2nd_ed_list.htmlClick on
Sheet 40 - Kinross.
Scoonie is the pink-coloured parish against the eastern edge of that map, a short distance above the centre line. Click on it a few times until the writing is legible and you will find Leven.
Loch Leven is across the map in Kinross parish (yellow coloured) on the centre line, most the way towards the west side of the map.
As the birth you are looking for is about 1907, you may not find it on the ScotlandsPeople website until next year (for 1907), or later for later years, when its 100 year closure has expired. In the meantime, it can be found in New Register House, Edinburgh, or Park Circus, Glasgow.
ADP