I pushed a stock C7AWE center into the mid 9's. I pulled the bearing support to fix an oil leak and found the pilot support was cracked. If it broke, it would spit the pinion out the side of the case.
I now use a Moser aluminum bolt through case but only use 31 spline Moser axles. With a powerglide, I'm not producing enough torque to the wheels to justify larger axles although I am pushing the limits of 31 spline. 33 spline for me is an acceptable upgrade unless I bought a 35 spline spool designed for the smaller case. If you use a 3 speed tranny then 35 would be a more preferable choice since the torque multiplication will be higher.
When I bought my axles, I painted a line down the length of both axles. I pull them every couple of years for inspection. The line and the splines are still straight and I've carried the front wheels past the 60' a few times.
I originally had Strange axles but didn't like them because the splines were larger than the axle. The Moser axle splines are the same size as the axle. Maybe Strange uses a different alloy to use a smaller axle but I feel better knowing I have larger axles.