I need your input, sorry, not Mopar related

Alright, my dad gave me his 75 Ford F250, big block 390, before he passed away. It leaks oil, BAD, as in I drove from Grand Forks BC to Vancouver Island BC, and went through 19 liters of oil.. Constantly pulling over and checking it and filling it again. I never once ran it dry, or ran it hot.
Anyways, I work out of town, in another province infact, and only get a week off at a time, so not much time to tear into this thing. So a friend and his dad own a lot with some buildings, and one of the buildings is rented out to a mechanic who says he specializes in 4x4 stuff. He has a bad history of paying rent, so instead, owes them a certain amount of hours worked on their vehicles each month for rent. They had about 10 extra hours last month, so told Toby (the mechanic) to fix my oil leak. The previous mechanics that my dad used, tried 3 times to replace the rear main seal, but couldn't get it. Turns out they cut it in half to get it in, and filled the gaps with RTV. They also used RTV instead of a pan gasket.
Toby had my truck for 2 months, and didn't fix it. Instead, he pulled the pan off, and let it sit. He pulled one of the main bearings, and found it shows a bit of copper. When my friend and his dad realized Toby hadn't worked on it at all, they threatened to kick him out if he didn't have it finished by the time I got home, which was Feb 1. He panicked, and put it in on Jan 31. I was so excited to have it again, I drove it into town, and it started spewing oil again, just ad bad. So my friend's dad is convinced that Toby can still fix it, so got me to leave it at the shop once again while I'm at work. So now, Toby thinks the crank is out of balance, is wobbling, and is ripping apart the rear main. He wants to have the crank milled, replace the bearings, and redo the rear main.

First question, am I wrong to think that maybe it is just the rear main again, that maybe he f*cked it up by rushing it?

Second.. If it is infact the crank, how common is that? And how much $$ am I looking at spending to get it done?

Third.. Give me advice here. The truck means a lot to me, as it meant a lot to my dad. I don't know what to do, and being up here working and not at home, means I can't do a whole lot..