removing old paint-well some of it !!

[db67]

hi, got a series 1 that i've had for a couple of years now that has been brush painted with household gloss !! this paint comes off fairly easily, problem i've got is it has red oxide primer underneath which i want to remove without removing the original paint that's underneath that ! reason being is i want to try & go for the 'rustoration look !' & retain the original paint, so just wondered if anyone knows the best way to remove the red oxide ! thanks in advance for any info. db