your decision of course BUT upper wishbones sure ain't cheap and cambelt, pulleys and waterpump change are about an 8 hour job .. 10 yrs / 100k miles
if the service history shows lots of this done then maybe the asking price is ok BUT if not done then you will know what you might be in store to expect
I've just spent the best part of £2k on mine this last year with my indy doing the stuff and getting proper parts from Amayama in Japan ( 50% of the UK Lexus /. Toyota cost )
BUT my knowing this stuff won't need doing ever again ( maybe )
The Mk3 Ls400 does fail the MOT on the wishbones at about 160k miles onwards, depending on the driving and driver over it's life
Your decision whatever BUT as I said, a fresh sensible MOT will show you if the upper wishbones are likely to be a cause for immediate concern and a potential bank balance drain
Good luck whatever
Malc