Almost nobody does pure Level 3 networks. People combine Level 3 with lower end providers such as MFN/GBLX/Cogent/HE etc.. They do this to offset costs. I think just about the closest you could get to pure level 3 is 1and1.com for dedicated servers. If there are others, I do not know of them.
Have a look around datacentres in Europe. Level3 is far more commonly used for single homed traffic; also is more in line with other transit providers price wise due to the higher (than the USA) costs of transit generally found in Europe.
I know for instance that Redbus Interhouse have just committed to a lot of Level3 bandwidth so as to resell to clients in their datacentres. It may be worth contacting them so that they can get you in touch with providers they know can offer you what you want.