Isaacson/Landro/Landreau/ Stordahl/Beckdahl-HELP!

Can someone please give me a shove in the right direction: Am looking for information on "Johann Stordahl" and wife "Jonetta Beckdahl", both possibly born in Stadsbygd, Prestigjeid, Norway. Have one source giving Johann's birthdate as Jan 2, 1812, and one source giving it as 1827, no day and month. Have one source giving Jonetta's birthdate as May 1, 1824, and one as 1831, no day & month. Have not been able to locate either in any "official" source to verify. Haven't been able to locate either in 1865 Census. One child, Anne Stordahl, b. May 31, 1847 in Norway, emigrated to Minnesota around 1875. Found her in Digitalarkivet in "Norwegians in Minnesota in 1880", wife of "Nels Landreau", who is listed in another source as "Nils Johan Isaksen Landro". Can find no record of their emigration, although that wouldn't help with the parents or rest of the family in Norway. Feel like I have tried everything under the sun, but I suppose I have overlooked something simple ... would appreciate a flashlight, trail of breadcrumbs, big pointy arrow ... anything! Thanks!