I HIGHLY recommend OEM on bushings, if you want to keep the Lexus ride, the polys make the ride hard and brittle. (my experience, I bought polys and in one week removed them)
PS: If you are a DIY type, do you own TB/WP and replace your seals too.
see : http://www.lextreme.com/timing2.html
and http://www.lexls.com/tutorials/engine/timingbelt.html
yours is slightly different, but the guide is the same.
check these parts prices, I have done 5 of these, using these parts, with NO failure, and MUCH savings.
http://www.store.partsdinosaur.com/page247.html