I don't see Currie or Strange selling 7/16" t-bolts for the Ford 9 inch rear. I see 3/8 and 1/2. Seems like 3/8" must be the stock size. The 1/2" would require redrilling the axle housing and backing plate.
FWIW, a Wilwood brake caliper only uses two 3/8" bolts to hold it in place.
If you do a little research, you'll find that the shear strength of a single 3/8" bolt can be almost 10,000 lbs. Even a low grade bolt can handle nearly 5,000 lbs.
https://www.nucor-fastener.com/Files...r_Strength.pdf