Project Azorian'esque conspiracies begin.
Naaaah, something of that nature is best built from scratch due to reinforcement needed. On the other hand, having a nice USNS ship with roomy berthing for a crew of 40 or so, and the ability to call "Birds Away!!" a couple hundred times rocks! I do find myself 'almost' missing the acrid yet sweet smell of spent booster fuel, the roar that shakes one's innards for a fraction of a second, and that rising arc as the 1st stage shucks off, with the sustainer kicking in for a exoatmospheric fireworks display.
At least that's the experience of this grumpy old man that stood the watch....