The 40's can be fitted easy, but to realise thier full potential you will ideally need mappable ignition, I would look into things in great detail, 40's will no matter how well set up NOT match the overall driveability of EFI, not in a month of sundays.
If wanting it for the induction roar, just convert to itb, individual throttle bodies, same noise but benefits of efi.
Having run 45 and 48 DHLA's for a number of years, despite the delorto dhla being a better carb than the webber, the amount of problems due to icing was unreal.
tabetha