Viking bows were way heavier than 40 - 60#. Replicas of the Hedeby bows pull 80 - 100 lbs., and the Ballinderry Viking bow from Ireland must've reached poundages somewhere in the 100's based on it's "typical Mary Rose bow" dimensions. Early Iron Age bows from Denmark seem to have been substantially lighter, as were the arrowheads of the time, both more in line with "typical hunting gear" of the present day. Iron Age bows from the North are of yew, with the exception of single juniper bows from Greenland, Sweden and Estonia. Living inside a millennia-long tradition of yew bows, I'd venture to guess the guys were quite inflexible in their selfbow material views. There are at least ten native woods in Scandinavia Iron Age bowyers could've used, but we have no evidence of oak, ash, elm, maple, elder, rowan, bird cherry, hazel, buckthorn or apple bows. Instead, loads of yew, with a couple juniper and the following:
Sagas do mention "two-wood" bows, and the compression pine belly slats from Early Medieval Norwegian cities confirm that the Vikings (or their direct descendants, at least) knew and used other bows alongside the yew longbow. The "western" wood laminates are markedly different from more easterly ones, indicating perhaps indigenous evolution of an eastern import.
Tuukka