Find a dealer with a glass specialist on staff or with a working relationship with a good glass shop that's actually worked on an LS 430 before and knows what the heck they're doing. Buy the real Lexus glass. Aftermarket windshields are crap. I've never seen one - not one - that even approached OEM quality.
The windshield on my LS 430 was destroyed by a rock. I had it replaced by the body shop affiliated with the dealer that sold me the car. They did damage to the car that so far has cost me about $2800, more to go... still waiting for parts for upholstery repairs from the sealer they dripped on leather, wood, and switches. When I complained about the incredible state of the car on its return they just stiff-armed me. Turns out they sublet the job to some cheapass glass shop downtown where they'd never seen an LS in their lives.
The whole job had to be done over, plus all the extra repairs and cleanups.
Lexus "respectfully declined" to get involved.
At first they tried to charge me $1200 for the glass, but later brought that in line, about $700.
They used the wrong sealer, applied it unevenly, left an unsealed gap across the base of the glass, destroyed both A-pillar trims, installed weatherstripping wrong, damaged structure around the glass to where other parts could not be installed in alignment, ruined the chrome across the top of the windshield but reinstalled it anyhow, tried to re-use the rubber seal around the glass and left it so wrinkled you could see the problem from thirty feet away, left with wipers misaligned, and screwed up the rain-sensing wipers. They dripped sealant on one switch, one wood panel, and on the driver's seat. They forced bent parts back onto the car in a lame attempt to cover up the damage. Weatherstripping was so far misaligned that the edges of the glass were exposed.
Spend the money and get it done right the first time.
-- Pete