Its going to look awesome on that amp of yours. I'm seriously thinking about going the same route, but with walnut (there's already a bit in the garage). Anyway, I don't think brass is going to be the best for this job. If you've already got the bits, long term, plating may be your best option. I think once you've bought all the laquers, etc, you might just as well have plated.
There's also some nice gold coloured alu knobs and bottons on eBay that I'm eyeing.