Soda blasting leaves a film behind. I do not recommend it. As far as paint goes, not all paints are the same . The lower end stuff has less UV protection in the clear. As far as base goes, Sherwin Williams and Dupont use parafin wax as a metallic control, which makes the base prone to stone chips. Base coat is the weak link in a base coat clear coat system. With black, I would use single stage with clear mixed 50/50 with the last coat. For a high quality restoration system, I like PPG. There are others that will give a high quality finish, but remember you get what you pay for. Cheaper products might look good at first, but will shrink, ring up, pinch up, die back, chip, peel, spider web, de-lam,etc. I have been in the collision repair/restoration industry for 15 years. I can make cheap products look great, but I understand the difference between a job that will last and one that will look like crap in a year.