78 W100 318 Water Pump Bolts

I am in dire need of water pump bolts for a 318 I pulled out of a 78 W100. The original bolts are pretty crusty and every set I find online are for newer 318s and won’t work. The older bolts have to be longer because the alt and PS bracket use the same bolts.

Does anyone know where I could get correct length bolts or what type of bolt (torque ability, metal, length, thread count) to use if I need to make my own?
Author: nballen_W100