A particularly nice shell is the Lotus 49B Monaco winner from the "Classic" range of fibreglass bodyshells by Betta & Classic.
A 49 can be made by cutting off the the shell from the rear bulkhead and grafting on a rear end of their Matra-Ford. I advise against using Classic's own 49 as it's a much smaller shell than their 49B and will be difficult to fit with a chassis other than maybe the Airfix slimline.
You can get decals for the 49 from MRE and Patto's Place.
Hope you find this information useful.