The alloys from my E Class Mercedes estate fitted my 408 as well -- looked horrible !
This company charge about £200 from memory to band and powder paint your existing wheels to enable wider / more popular tyres. At least they look the same and take the original hub caps this way.
www.bandedsteels.com
Quite a few Hot Rodders / Grass Trackers use this method - MAKE SURE YOU GO TO A QUALITY EXPERIENCED COMPANY. Safety and all !
Greg