The Nydam bows are not Viking, they would be considered early Vendel. However, the ships found at the same site are defenetly a predecessor of later Viking ships, thus from the culture that became the vikings later. The Nydam bows are basically just a long yew bow with one sidenock. They are predecessors to the later Vikings bows. However, as a few hundred years passed, it seems like bows were made stronger (the two finds are defenetly bulkier, probably 100+#). That is probably the reason for the bulkier nocks, as soft yew wouldnt stand that strong a bow without reinforcement of either horn nocks wich came later, or more material. Deflexing the tips can be for the same reason.
If making a bow for hunting, say 50#-70#, I would not recommend the tip configuration of the viking bows, as that would leave you with heavy outer limbs, resulting in poorer cast and mor handshock. If instead assuming the knowledge for making a good weaker weapon did not dissapear in a few hundred years, you will get a better performing bow by making a Nydam bow.
If making a yew bow without hornnocks designed for a long draw and say 120#, I would make a Heithabu replika. However, even though I am of viking heritage, modern life has left me to weak to have full controll of a 120# bow, I have enough trouble just pulling and shooting one.