engine6069, sounds good. I have some second hand experience with such things...my dad co-founded a group that did the same thing...and spawned many similar groups across the country. I don't know the experience level of your group, so I'll presume you don't have prior experience with something like this.
For a full overhaul (which I get the impression you don't intend)
I would roughly estimate that you'd probably be looking at $400,000 worth of running gear work...as well as plenty of boiler work (in the US you need to strip everything...and ultrasound test the boiler)....which would include repairing the boiler tubes, superheaters, possible firebox patches, and piping. One of the last steps in boiler work is hydrostatic testing. All of the appliances would need to be rebuilt. It probably needs a zillion new staybolts. The frame may have cracks/damage that needs repairs...and you can't know for certain that it's okay until the drivers are out. It appears that 6069 has been outside for decades, and it sounds like it's mostly worn out parts.
In short, focus on a cosmetic restoration unless you have experienced people in your group. There are many half apart locomotives in the US/Canada from unsuccessful restoration attempts. If you want to see her restored...work slowly & carefully. Bring in Scott Lindsey or Gary Bensman before ripping her apart...if you want to restore her to operation.
The single best thing you could do for her would be to get a roof over her, and maybe a wall to shield her from the north west. Working under a roof is far better than working under the rain.
Good luck! It's great to see local groups caring for their treasures!