First and foremost, I think it looks great as it is. I know you wanted more contrast between the padauk and the purpleheart, but there's lots of other contrasting pieces in there to add interest and the purpleheart and padauk may very well change in time anyway. I think you could get the old finish out by repeatedly washing it down with naphtha, but keep in mind that the naphtha will be getting into the pores you're trying to get the oil/conditioner out of. If you're planning to use it for actual food preparation, that's not good. Also, naphtha is very flammable, so be careful if you decide to use it.