Fork needs to be rethreaded about 5cm, and then cut down to match the headset..5 cm is quite bit. Is the fork steerer chromed at all? You can't cut threads on chrome. This would be the most expensive part of the install.
crown race needs to be installed..assuming they are the same size this isn't a problem.
possibly a new headset, something of the cheaperish tange levin variety. It would be easier to buy a headset to match the fork opposed to using the old one. The crown race diameter is the one to watch out for. Just install in the $50-70 range I would think.