For your current situation, I'd forego the timing chain. Just another thing to go wrong in a race against time. However, definitely check the timing chain cover bolts. They are known for coming loose. A bunch of them were hand-loose on my XJ.
Also, you should only use distilled water or anti-freeze that's pre-mixed with water. Tap water is bad for the cooling system, so after you get the cooling system back together, the first thing I'd do is flush with distilled water and then either use pre-mixed anti-freeze or refill with distilled water and straight anti-freeze.