Should be easy-enough to do. 'How' you strip the old paint is up to you, and to what extent you wish to go. You could simply lightly sand it back, and not remove all the paint; you could use brush-on paint stripper. Or you could dismantle the amp and take just the cover to a sand/bead/metal blaster and have it totally stripped.
When done carefully and with patience, I'm sure you can achieve 98% of what the last option offers, by doing only the first option of sanding by hand, paying attention to detail and ensure the surface is well-prepped. I'd be dismantling the amp, either way.