I think your two options are (if you want to do this properly)
1. Paint will not properly adhere to the chrome, so, sand or grind of the chrome, rust etc, fill pits and irregularities, sand to proper condition for painting, properly prime, paint and clearcoat. Removing chrome probably requires use of special filtration masks.
2. The same, except have the fork re-chromed instead of painting. Classic and vintage car part restoration services is probably your best bet to do that.