Have you tried poorboys black hole polish? Really good at masking swirls on dark colours. Would use a wax/sealent over the top though, wont last longer than a week i find. I can recommend autoglym super resin polish, good filler as well, as its easily purchased at halfrauds. Autoglym also do a polish specificly for darker colours, not tried it although ive got a bottle somewhere. Would also recommend using a claybar before polishing, i have found without, the results are almost night and day and the polish bonds loads better.