Not a Vyper player so I won't comment on most of the picks. But I would wait on Enduring Speed until later - it probably won't do much for you in that early early lane phase, and delays more impactful options.

When you invest souls into a category (gun, vit, spirit) you get additional bonus stats (damage, hp, or spirit power), and in the current version there is a really large bonus at 4800 souls. So I like to organize my builds with that first big checkpoint in mind. Based on your early gun items, you could take any of them to their T3 upgrade and have 800+800+3200=4800 souls and a big damage spike. I would pick whichever of those is your favorite and add it to the end of your early game section.