I don't think you can go wrong with a Leup M8. I have owned 2 myself, though in my family has been over a dozen M8's at one time or another with the same results as I experienced - rock solid. I still have a M8 4x, it is the scope I reach for when determining: gun or optic issue!!
Sounds as though this rifle & scope will be a range/show piece vs hunting??? If so, I would personally opt for a 6x even at100 yards I like more mag now. If 100+yards even better IMHO. If not and it may see hunting duty a 4x is the safest option better for close and doable for longer (of course you'll be well practiced to take such a shot and know what to expect/do

).