im a 3rd generation metal finisher plater , so buffing an aluminum tube is not a big deal custom metal finishing was 33 % of my business you would not use Tripoli on alum its used with a sisal on steel stripping may or may not use acid it can be done with caustic also as for removing the fire safe engraving if you are a pro that wont happen , as a restorer you try not to mechanically strip if possible you have more control chemically stripping , you can also reverse etch the part to strip.