should be fine with the engine in situ 🙂
as the mileage is near 100k, I would advise replacing both chains.
the cam chain kit is about £100 including tax in the uk, the balancer chain is a similar price
the timing is very easy, no special tools required, just use a cable tie to hold the cam chain to the sprockets whilst timing them up, make double sure the crank chain is timed correctly, it's very easy for it to jump a tooth during install.
Just double check the marks before refitting the timing chain cover