I totally agree with not using a heavy media for shotblasting. I want the lugs crisp, so I think I want to remove the paintwork myself by hand. I need to inspect the steelwork underneath the paint before I give it to a professional frame painter anyway.
I think my direction would be to remove paint by means of a chemical stripper, carefully applied with a brush as not to get any inside the frame. Once the paint is removed I will smooth it down by hand. It's then when I will be able to see if I need any brazed fillings. I have been in touch with a great frame builder who is happy to help out with these fixes.
Thanks for everyone's advice so far!