6 weeks is still very young. The fish will progresively become more territorial. It could be war tomorro or war in a year, it's hard to tell. However, nothing good ever comes out of jamming a bunch of fish into any tank reguardless of size. Once one tang establishes his territory he may no longer let the other ones around it. This will only cause stress to the others and could bring disease to the whole tank. It is highly reccomended to have a 6ft. tank to house multiple tangs. In the wild they swim miles per day so 6ft. is not asking much. Although I cannot talk because I once had a 90 with a YT and a BT in it. I would have never thought to put in a sohal though. I think your making the right decision to get rid of the LF's and a tang or two.