best driver's seat for 123

[seo]

The snow is receding, salt washing away. One more rainstorm and it will be time to start up my 1983 300d turbo. This is my third W123, bought it last summer, and the driver's seat is not particularly comfortable on a long drive. So, a couple of questions:
1) What's the nicest seat that will work in a 123? I've driven 420SEL's, and their power seat is pretty nice. Will that fit in a 123? Any other better seats that anyone knows.
2) Are there aftermarket seats that are better than Benz? I don't need high style or race-car support, just a really comfortable and functional seat.

Any ideas would be appreciated.

SEO

[joadjr]

I use an Obus brand aftermarket back support that straps around the seat along with an Obus tailbone cushion in my 123. Picked both up on ebay for very little $. Both of these relieve my back of the pain I usually have from long distance driving. Of course stopping regularly and walking/stretching helps too.