X2 for getting hold of FSM and going through the items one by one.
In regard to the steering box, you can buy an OEM new one for around $400. In my opinion it's a good investment to make if the steering is loose. I can't see the value in persisting with loose steering, others will likely differ here.
Personally, I change all oils when I get hold of a car. Diffs, gearbox, transfer case, engine. All filters as well. Oil, fuel, air. Who knows when these were last changed in any given car, perhaps there's water in a diff (a quick check of the oil will tell you this, pop the filler plug out and dip your finger), it isn't a big deal to start from fresh. I like knowing what is circulating in the bits of my car.
Grease the drive train. Check and inspect everything as I go. Inspect all hoses etc, the FSM will guide you through all these.
As per Steve, kingpins and bearings need to be checked as do steering knuckle seals and CV grease etc. again, when I'm getting my new cars ready I plan for a rebuild on the steering knuckles and replace kingpin bearings. Re-grease all and change when bearings as I go.
Again, not everyone will agree with me here however when I get hold of a new car I like to reset everything so I've got a starting point. Once these things are done, I know they're done and done well. I shouldn't have to worry about them for a long time. Plus I've never seen an older car with these things in impeccable order, thus I like to make sure they are sound.
Also by doing these items I spend a fair bit of time staring at other components and usually end up finding a hidden issue here and there.
Make sure the carby is working soundly. Make sure the automatic choke is working (assuming its stock Carby or if not, assuming it's fitted with a choke mechanism). Does it drive well?
I also like to look at wiring as I go. I'm not takin about dissecting the entire vehicles wiring, but following the wiring harnesses within reason and see if anything jumps out as unusual or badly installed. Many old cars have had some serious wiring butcher work done. Spotties wired in badly and hacked out, wires cut off that serve no discernible purpose or just bodged up with many miles of insulation tape. I like to remove unnecessary wiring that loiters about and tidy up bodgy work. It might just save me from trying to fault find an electrical gremlin in the dark somewhere along a highway miles from nowhere.
This is the result on wiring when 4x4xzook's battery was a little loose causing a wiring issue. Sorry to steal you pic 4x4xzook, I don't know how to link to your thread. Inspection might (and I stress MIGHT) pick up on an issue like this before it becomes a problem. Stuff like this is likely to crop up here and there regardless of how much time you spend checking the car over
Hope that helps