You need to polish the corroded steel where the nickel plating has gone, then when you spray over it will hardly notice.. you might have already got your head around this, so sorry if I'm teaching you to suck eggs..... :roll:
last time I did this (pre-membership of RetroBike) I first treated the corroded areas with a rust treatment, I would now recommend Evaporust, then scrubb the areas with a green washing up souring sponge (less aggressive than Scotch pads) using MAAS concentrated metal polish, then again with a soft cloth to put some shine into the bare steel..
Beauty of this is the MAAS will protect the raw steel for months (if it takes you that long to do the whole thing), then when you're ready to spray, a couple of good rub downs with an appropriate spirit,thinners or petrol, then a final wipe with alcohol and you're ready to spray on a candy/flamboyant/translucent paint of your choice... it will look the nuts :xmas-big-grin: