When I built this Schwinn Traveler for my friend's daughter he requested a "modern" drivetrain, so I built it with an 8 speed Sora group. As it didn't have shifter bosses, I used a standard vintage DT cable clamp, such as you might find on an older bike equipped with stem shifters. It worked very well.

In addition, I would always put some sort of barrel adjuster on shift cables, because they can be very useful for trimming while on the road (front - not so much, rear - always preferred). I think it is a good general idea to have them - they cost next to nothing, are easy to install, and provide a nice convenience. IMO they are a particularly good idea on any bike that is rigged with high gear counts on the rear. If the RD you're using has one, that is usually good enough.