Why would you want to upscale to 4K? Why distribute a (Indie) feature in 4K? Where, on what? Why would an upscaled Bluray (if it yet existed in 4K) or DCP in theatre look better than the 2K if the source footage is only HD? And you can´t "scale" to anamorphic, you can only crop to get the same aspect ratio. You are mixing a lot of terms and most of it does not make any sense. My advice: Shoot in 16:9 Full-HD, the native raw format, then upscale to 2K to export a DCP for theatres and vertically crop it on 1:2,35 with letterboxing, that´s it.