Yes, as long as you could keep it straight.

Maybe thread a new bushing onto an "all thread rod" and then thread the "all thread rod" into the existing bushing to align the new extension piece. Then use a sleeve over the old bushing to the new bushing for the actual welding so you are not welding the "all thread rod" in place. The "all thread rod" would just keep everything perfectly straight for the weld between the sleeve and the old and new bushings.