ORIGINAL: AZHuntr
I actually plan on staying at 70# for a while but would like to be able to go up in poundage if and when I do an Africa big game hunt (dream for now). So from what I read of your post you are suggesting to buy arrows for what works at 70# and if I move up later then buy arrows for that weight increase great idea!
That's exactly what I meant. If you're like most people you're going to be replacing arrows periodically so yo buy stiffer arrows as you move up in weight. To pick the right sine pay more attemtion to the manufacturer's selection charts.
Just pulling info from experience, but with your draw length and 70# you should probably be shooting something with a 340 spine. This might even work OK up to 80#, but I'd think more like a 300 spine for that.