The chrome molly shafts will be stronger as a shaft, but the u-joint ears are not really any stronger due to the material removed to make the hole for the 760 u-joints.
Those shafts are cut for circle clips, which you should use. But in addition, consider spot welding the cap to the ear. The cap won't spin/ throw the clip and should save your shaft ears from a thrown cap. Infact, you can take a stock shaft and do this, but the next thing that went was that I twisted the axle at the splines.
The 4.56 gearset is a weak combination for a LP 30 with upgraded shafts.
I know people who have tubed and trussed their axles to try and solve this.
I'm not sure it helped, but I have replaced (3) 4.56 gear sets in a LP D30 and don't ever plan on doing that combo again.
Ultimately the solution that DutchVDub lefthandedly suggested.
Drive with finesse, and like you want to drive it home instead of trailer it, and you should be golden.