Newbie looking for opinions 57 GMC (sorry a bit long)

[Fred D]

OK here goes
my wife's family owns a couple hundred acre ranch that has this 57 GMC truck on it. Truck is been on the ranch for the past 25+ years.

For about the last eight years it has not been running.
Needs tires-Carb-steering components and brakes at the bare minimum. And also add A/C
My daughter is about to turn 15 and she said she would like to have his truck as Her daily driver… Wouldn't we all.
I asked the family if they would be willing to sell it and I was told absolutely not since it belong to one of the patriarchs of the family my daughter's great great grandfather who bought it new.
Since it has not been running or driven in the last 7-8 years i thought I'd take a different approach
I ask if they would be willing let me do the repairs at my expense (parts and labor) and get it running and safely driving and then my daughter Would use it while in high school, then my son would use it while he was in high school then I would give it back to the ranch.
The "owners" agreed that it was ok.
Now I am questioning my idea.

I'm not opposed to dumping some money into it, but I'm questioning how much I'm willing to spend on the cool factor then to give it back.
Also, I will still need to by them both a car for college.

I have briefly looked at kits to make the front end more modern with coil springs and disc brakes. Found them for $3500-4K That is way more than I'm willing to invest to not be able to keep. I know it can probably be rebuilt back to factory specs, but when your putting your kids in it, you want them to have something that can stop quick.

Speaking of safety, want to move gas tank from inside the cab also

Ok
Looking for suggestions on fixing the truck to make it safe and adding A/C, or opinions on whether to try to move forward or abandon the idea and go a different route
Thanks in advance for your input