I prefer to make my 7-08 brass from Lapua Palma brass, giving me access to small primers. Simple neck down. 243win pulls up to 7-08 just fine as well. Don't use the expander ball in the sizing die, use a bushing full length sizer and neck down, followed by an expanding mandrel die. For 243win brass, I work the brass more because I expand the neck with the mandrel first, then full length bushing, then mandrel again. I use at least two steps of expanding mandrel to make that change, sometimes 3 steps - 25cal, 6.5mm, then 7mm. The more you ask it to expand at a time, the more apt it will be to pull thin spots and eccentricities between the neck and body. So I take my time, neck up 2-3x, reset the neck tension and re-center the neck to the body, and then re-expand to 7mm. 243win brass can also leave a doughnut at the base of the neck in some brands, as you're pulling shoulder out into the neck. So that's at least three advantages for using Lapua 308 Palma brass - easier sizing, less likelihood of doughnuts, and small primers for longer life.
Lots of options for marking your brass.1) Use 1 specific brand for your 7-08 loads. 2) Stamp an indicator into the casehead of all of your converted brass. 3) Paint a ring of automotive or modeler's paint around the extractor bevel of your converted brass. 4) Use a file to carve a small notch in the rim of the converts. 5) Sort at the bench by slipping the tip of a loaded 30cal round into the neck... Lots of options, some work better than others for different folks...
Usually, I keep my stuff pretty well segregated, so marking isn't critical for me.