By the way, if the consensus is sticking with this tank and scrapping the plywood 180g idea, I'll take all the stuff you got thanks to the good deal I got on the tank!
I've probably read every thread on diy overflows in this forum to the point that I'm going crazy! I guess I had come to the conclusion that a drilled tank would look much tidier, but not necessary as far as functionality goes. I guess my main concern is if my Brown Knife will be happy in a 6' long tank when she's full grown. If so, it'll cost me hundreds less to just use the tank I've got now!