Wow!
Honestly if you are doing a tank-to-tank move in the same room there isn't much to worry about. Plus, it sounds like you will be moving alot of the seasoned pieces ove (sand, rock, water). I think your biggest concern is the extra 100G of water you will be adding. If it were me, I'd try to syphon off some of my water each week during water changes and store it in a separate tank. However, I only have 46G total. So, I'd be concerned about doubling the water volume with all new water. Also, when thinking about your existing 100G, you won't be able to keep all of it anyway. You'll want to use some to rinse out your sand which you will want to dump at least that if not more "dirty" water. So, you're looking at even less water carry over.
The final think I think you will encounter is LAAAAAAAAAAGGGGGGGGG. Getting a new tank up and running ALWAYS takes longer than you think. I hope you have a good container for your livestock. You'll need to keep that temp stable while you put the new one together. Plan ahead for all of your rock placement and buy extra supplies from Home Depot. Adding 45 minutes to a build is much more frustrating then spending 45 min returning unused crap.