Helpfully, item ID conflicts show up in the log as well, even if they don't cause a crash. What I normally do is once I get the block IDs resolved, run the game once and do a block\item ID dump. Then I check the log, do a search for the word "conflict" and fix anything there, and do a general scan for anything that stands out as unusual (GT has a lot of things in here, trying to overwrite pulverizer recipes etc).
Backpacks etc I always do later rather than right at the start, always too impatient to play
Backpacks etc I always do later rather than right at the start, always too impatient to play
