Yeah, the numbers do seem low to me, too. I wagged the combined altitude/plane change vectors, so maybe I did that part wrong. That's what happens when you let work get in the way of writing a good post.

If you could use all 21,000 kg of OMS propellant, you'd still be over 50,000 kg shy of what the numbers seem to indicate Columbia would've needed to dock with the ISS. To put that into perspective, the maximum disposable payload for a Shuttle is somewhere around 24,000 kg, less than half the propellant required. That isn't even counting the mass for the propellant tanks, either. They're pressurized to a few hundred PSI, so the tanks would be pretty heavy. The total extra mass needed would be more than twice the Shuttle's cargo capacity. Short answer: no way, no how.