It's illegal, but you could have the taper welded up, and reamed to the smaller size.
"THOU SHALT NOT MAKE A WELD UPON ANY FORGING WHICH IS EMPLOYED IN SUSPENDING OR STEERING A MOTOR VEHICLE"
However, done tidily, it's impossible to prove it's been done. However depending on the metal used, it might go hard as fuck and need to be annealed before it can be reamed.
Since you're not a welder be trade @MaxPower please dont do that. ;-P
And if you do please use a gasless MIG or damp welding electrodes. (With 5 pairs of sunglasses)