Well the 075 was a great old beast of a saw, and would be one of the best machines you could use for milling.
You have to make the call on how much money you put into it, but with a proper rebuild it should so the job as well as a $1,000 new saw.
I wouldn't look at it as what the saw is worth after the rebuild, it might only be worth $200, but rather how much cutting it's going to do for you over the next few years.
110cc of old school Stihl torque there.

Again, check with Chainsawr regarding parts, and the guys here can probably advise you on how to strip it down and rebuild it yourself.
Ian