The lights come with a 6 pin connector regardless and are not auto levelling, you will lose that function. With regard to legailty, I don't think it is illegal to not have it when they can be adjusted manually.
I went for the preinstalled HIDs as compatibility was a concern.
Safe bet I'd say is to go for the preinstalled HIDs as we know the lights will arrive in a plug and play state for a JDM car. If your 350 is a UKDM the original 8 pin connector can be swapped over/rewired to replace the 6 pin and they will become plug and play.
Hope this helps