I'd sooner put a short mag tube (easy to cut down) than chop or thread a 30TK. They only made them for either 2 - 3 years. I almost made a mistake by selling mine a very short time ago, and came to my senses in time. You certainly got a great deal on it! Find a regular RC model if you're going to cut it anyway, or thread it. You can shorten a mag tube with a hacksaw, some sandpaper and cold blue pretty short without getting into the forearm, they can also be replaced pretty easy.
But it is yours to do with ad you please. But I'm bettin someone will swap rifles and offer some cash to get their hands on a TK. Where's the pictures?
Oh, Welcome to MO from Kentucky by the way!