HatTrickPatrick

I have a world save a friend sent me that I'm trying to edit into my server as a new dimension. I used JustEnoughDimensions to create the new dimension so I have the "DIM-" folder to copy it into, that part's all good. However I found out from him that he was using mods on his client when he made the world. I'm fine with that, all the mods he was using I've installed as well. But I got to thinking and realized that his world's level.dat file would probably have a very different set of ID associations in its registry than mine does. Lo and behold, I opened up both level.dat files side-by-side in NBTExplorer on my PC and the associations are different. Is there a way to replace the associations in his world save to match the ones my server is using? I'm assuming that such changes would have to be made to the blocks, items, etc. in his world save so that my server recognizes them properly.

AFAIK there are two mods in existence that can disable the checks on entity/player movement, "Player moved too quickly" or "Player moved wrongly" - MTQFix and GottaGoFast - but they are both coremods performing bytecode replacements... Is it possible to circumvent these checks with the API, or is a coremod the only way to do this? Thank you for any helpful info in advance [EDIT] Occurred to me it might be helpful if I were to specify & link to the two mods I mentioned instead of just pointing out they exist [/EDIT]