Getty Design supposedly has some great stuff - their carbon fiber decklids are supposedly incredible. Their fiberglass stuff is also supposed to be pretty nice with minimal fitting. AIR (mentioned previously) and GT Racing are other options, but get out your bondo.
I have a rear bumper from AIR that is a POS and will be giving up on and getting a Getty one to try them out down the road. I just got a GT Racing wing, and that will need some work to smooth out and such, but it was rather straight and will only need minimal work, so I would recommend them (but based on one purchase - I have heard others having real issues with their fenders and such). Of course not a single threadsert is in the same location one side to the other, so any concept of symmetry for my spill plate and wing mounting is out the window.
As for Sheridan, I would definitely recommend his stuff. It will also need fitting like all fiberglass (which you should know is okay - no two cars have identical body lines, let alone perfectly shaped body lines) but is the nicest, smoothest looking kit in my completely biased opinion
I have the same kit that Bill has - the standard width kit. The wide body is a whole other dimension... here is Roger's personal car
Click to view attachmentanother wide body that I like
Click to view attachmentand my POS before heading to the chassis shop getting a tube frame (with the standard kit) - notice the rear bumper dips at the center and I have spent hours sanding/filling/sanding/swearing/swearing/apologizingtoneighborsforswearing/sanding/givingup. I have more body work to do, but final fitting and such will all be "last step before paint" processes.
Click to view attachment