There are lots of variables to consider. I shoot 70 lbs also, with 29 draw length. I shoot a WB rest - modified by cutting out some bristles to allow vane clearance. My arrows are 29", 2315 aluminum with helical fletch. I shoot fixed blade heads. I can shoot 125 and 100 gr heads and both fly well.
Your setup and the exact arrow you use may be better suited to 125 or 100, as the head weight affects the overall spine (stiffness) of the arrow. Increasing the head weight decreases the spine. There are lots of charts out there, like the one at Easton's site, to help you select the proper arrow/head weight combination. I tend to pick an arrow in the "middle" of the range of recommended arrows. Getting good flight is what really matters and that may require some tuning of the bow/rest too.
The deer won't know the difference. I get passthroughs with my 100 gr heads.