That said, your very very very far outside of anything close to a recommended tang#/tank size ratio, so far outside of it that you are basically guaranteed to not receive a single post saying that your OK.  If you want to keep the tangs in the tank... well, its your tank, no one is going to stop you but you might as well forget about asking for help or seeking validation because its simply not going to come from people who have experience with these fish.  

Personally, I have a 3 ft long 57 gallon aquarium with a single yellow tang, and I have received at least one comment from an LFS employee that I should not have that fish in the tank... but they regularly stock and sell tang species that grow to about2 ft in length... and they have no problem doing so yet the number of tanks in the state that are capable of housing such an animal are probably less than the number of these animals they sell in a month, every month.  

You can keep the fish, they might even live for a while and grow, but the reason your getting these responses is that its simply not anything close to a viable long term (or really even short term) strategy and your pretty much guaranteed to have infighting, injuries etc.  Tangs as a species have a very thin slime coat- which is why they are typically the first to get and die from ich.  So, if you had ich once and you did not remove all fish from the tank for a few months, and then bring them in one at a time through a quarantine tank for another month or two to observe them... you still have ich- so when your tangs get injured from fighting, hitting stuff, whatever, they will get ich again.  

Hope this gives yet more perspective on why everyone says ... no.