Soft Ride 11" 412-4232C 90/130lb - HD version # is 412-4005
Standard 11" 412-4233C 115/155lb
Standard 11.5" 412-4201C 115/155lb
Heavy Duty 11.5" 412-4236C 125/170lb
I don't know the HD # for the other versions. I've got 4005s and they're quite soft with my 180lbs. I ride on the top setting all the time. With a pasenger you're likley to bottom out on large bumps but they're great solo.
Heres the contact info for progressive and part #s for the inserts.
Progressive tech line: 760-948-4012
Literature: 877-690-7411
Fax: 760-948-4307
Inserts: Metric & US size set- Part # 5011-008
Metric (14mm) set- Part # 5011-051
Apparently stock shocks of suzuki intruder 800s work too but I beleive they're 12in.
As to the sore tush, I did and advocate DiamondJims seat mod.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1239796388/13#13I did a poor job of it and just cut the stock foam down (too far) but even as poorly as I did mine its way way better than stock. It does lower the seat height though so if you're long legged the knee angle may be uncomfortable. This seat mod with EdLs forward controls approximate the feel of the stock leg position.