I'm not a big fan of sandblasting purely because I think it will damage the welding. I used to repaint frames as a hobby but due to space restriction I can't anymore. Anyway, if you powdercoat the frame, you will not be able to touch it up and you have to apply the decals ontop of the powdercoating. If you pray paint it with Duco car enamel and then put a coat of 2K clear enamel (car paint) over it, you can cover the decals and they will last forever. The reason you use normal enamel for the "colour" is because it dries very quickly and you can do the clear coating about 2 hours later. Before you aply the clear you must first apply all the decals. Give it thin coats of clear and sand it down after each coat. This will get rid of the edges that the decals will make. You can also go a step further and have stencils made instead of normal decals. Stencils is basically decals but it is reversed out and you will remove it after the name is sprayed on. With this technique you can give funky designs and pattens to the name that you would not be able to get with normal decals and you will not have to apply that many coats of clear to get rid of the edges.
You can always contact Cycle Art in Vereeniging. They do alot of cycles and can get it in original colours and decals if neeeded.
Hope this help.