So this is why it leaks badly now, the bottom of the plate-engine and timing cover-plate joints was not tight.
were the broken bits in the pan?
If yes then we still don't know why you had the initial smaller leak
If no, then the previous assembler did the damage and this -may- be why you had the original smaller leak. You just made it worse.
That cap may be reparable if you can find someone to clamp it flat and then tig or braze up the broken edges, then drill it out and put nuts/washers on the inside.
You might also make a heavy 'saddle' to span the two holes that you could thread it would need oil drain holes in it and might be tough to make strong enough, but something like this:
it would need to be strong enough to stop the leak AND hold the engine to the truck. not clear there is room to make it beefy enough
I don't see much meat to what you have for new holes. The two smaller holes must be oil drains for the timing cover
If you can't repair the cap then I think you need the engine out, stripped and off to a machine shop along with a cap from an junk engine