Alright, I got the conversion done last week. The parts needed for a 2001 UL (and I assume 01-03) are:
48603 (RH) and 48609 (LH)
48680 (parts 48157B (RH) and 48157C (LH) are included)
48510 (RH) and 48520 (LH)
Tanabe Springs NF210 or 48131 (RH) and 48132 (LH)
48341A (RH) and 48341B (LH)
48257C (RH) and 48259A (LH)
48530 (RH) and 48540 (LH)
Tanabe Springs NF210 or 48231A and 48231B (if you order the Lexus springs you do not need part #48258A. It will be included.)
All of the other parts and nuts are interchangeable and can be reused from the air setup.
All parts ordered from Sewell were $852.31 including shipping. The Tanabe springs were bought off ebay for $224.00 including shipping. The labor was $660 including alignment and took an entire day (9 hours). So all told, I spent $1736.31 to replace the suspension.
The ride feels much better and it doesn't feel like you are hitting a curb each time you go over a bump anymore. The technician told me that all 4 bags had slits in them.
Here are the pics:
Front wheel gap:
Rear wheel gap: