as a last attempt i would try 1200 wet'n'dry with some autosol. go round the tube not up and down. take the stanchion out to do it.
£112 each from wemoto.
£165 a pair for rechrome from
Pitted Forks. you could also try
Dynasurf as well. try doing a search on Google and phone around. BTW there are a lot of people offering the service but get it done by someone else.