Lylyl, it is completely fine to chin at 80 Ranged. Although, you may find that xp rates are lower than those at 85+ Ranged. I started chinning at 80 and had no problem
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~Dadadadadadada
Lylyl,
I see you're already 84 Ranged. You'll need 44975 Red Chins, assuming that you'll be getting an average of 220xp per chinchompa. At the time I replied to your post, it will cost you 35,890,565gp. Sorry for the late reply by the way.
~Dadadada