You are indeed lucky, nice find, especially for the money. Yes, I'd say 70's.
Only you know if it's worth restoring, you won't make your money back but it will give you solid reliable transportation.
As you suggest replace all the cables, inner and outer. If those tyres are the originals they'd probably need replacement due to perishing. Inner tubes may be okay. Rear brake blocks look to be missing. Check if there's any play in the cranks for bottom bracket wear. I'd get rid of that handlebar tape and put on some period correct grips.
Check the wheels run true, you could also remove the axles and regrease the bearings if you want to be thorough. You'll need a few simple tools to include spanners, Allen keys, tyre levers and cone spanners if you do the hub bearings.
Clean the rest and you'll be ready to go. Is it the correct size for you?