I am very sorry for this way too late reply. This was asked before I was a mod for this game, so back then when it was posted i couldn't answer this question and later on, I honestly forgot that this was posted to begin with. Anyway I have asked multiple people about what we should do for IL runs and we all agreed that it should be done in Single World. One factor for that being it takes away outside factors from a complete run in general like: do you start with a shield or not, because you got hit on the previous boss or the amount of extra lifes you start with. It is also way more entry friendly that way, because if ILs were made in Arcade, everyone would have to do a full run until the world they want to submit for. I am going to make an exception for world 1, since it makes no difference if you start world 1 through Single World or Arcade. So if someone tries to go for an Arcade run but gets a really good world 1 they can still submit it to the ILs. Both difficulty selection and level selection needs to be shown at the start of the run or in case you submit a world 1 from an Arcade run, show that Arcade was selected and the difficulty. I am going to update the rules for this. Again, sorry for this way too late reply. I hope this will clarify it for you, current and (hopefully) future runners. In case anyone has still questions about this or is looking for advice, feel free to message me.
