Worn Sprockets will wear the new chain, I'd replace the timing chain SET, not sure if your talking just the chain or the set.
Is the motor an interference fit? i.e. if the chain breaks will pistons contacts valves or not?
I know a guy who had a 5.2L V8 have the timing chain break at 230k miles. It was not an interference fit motor, so it just left him stranded, but the cost of a tow is more than a timing chain set.
If they stretch, the valve timing can be off, not enough to create problems, but maybe enough to loose a couple of HP, as well, make the pollution check a little harder to pass. If you've got it open, I'd spend the couple of bucks for a set and change it out.