Hi, other members here have more knowledge on what to look out for on the 430 than me but I can chip in my 5cents..
I have 2002 with 102000 on the clock and it came with problems due to not been looked after that well. Major service missed with the timing belt etc, cheap parts, a little neglected overall. However I did get it cheaper than most and I don't mind spending the money and time to get it back to running right.
What I'm saying I guess is that for a 2001 it's got to be looked after, fully serviced, timing belt should've been done and potentially water pump, regardless of mileage. Check for water in the boot and holes in the exhaust, other than that like any car press all the buttons make sure the roof operates smoothly, mirrors seats etc... Have you taken one for a spin yet?
I've had a few Lexus now and for me I've never felt the fear of breaking down, smooth comfortable confident drive but like any car it needs to be looked after properly. I think there's a detailed write up on clublexus about sc430 purchases if you do a search.
Cheers
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