The head gasket was obviously leaking, that explains the coolant in the oil and #3.
The rear seal streaming oil will be real difficult to properly repair without pulling the engine. Likely there will be some crank and bearing damage from the contaminated oil, or just from wear.
My suggestion would be to go ahead and pull the engine, get it out where you can see what's there. It's really not that much more work considering the option of laying under it with oil dripping in your face.
Something else, if you are not aware, the cylinder liners just sit in the block with oring seals at the bottom. If any move up, the seal will be broken and the liner will need to come out to be resealed. Not an easy job when sediment from the coolant gets under the liner!
Those seals really need to be replaced anyway, at their age they have to be deteriorated.
I've done inframe overhauls before, but usually when the engine was in relatively good condition other than smoking. Even then it's a big shortcut than can easily come back to haunt you.