I have a '58 861 also. As others have said if you want to keep the loader, you can add power steering. You are probably looking at around $1100 to add this feature. There may be a cheaper solution since I have not looked in a while.
I don't know what all you plan to do with your tractor. It is a good plowing tractor. I think it is rated to pull up to 3-14's as far as a bottom plow but I would recommend no more than 2-14 or 16's. It will also pull a 6' 3pt disk, and a 6' bush hog (rotary cutter).
I would not recommend using a tiller with it because the ground speed is too fast even in 1st gear.
If you plan to tune it up I would suggest using Autolite 437 spark plugs. You can change out the points for electronic ignition. I had this idea once until I priced it. You can buy several sets of points for the cost of the electronic.
Your tractor has a 172ci engine which produces 48hp engine and 41hp at the pto.
Good luck and enjoy it.
Thanks for the tips kf4uda!
bucktaker - I'll get some pics soon. I bought it this weekend but didn't have a trailer handy. I am going back up tomorrow to get it. I have also heard that saying about the dirt and keeping it on there or it will break down.