Top 2 probably wouldn't survive the blasting process and bottom 3 would need linishing back to smooth but again they could be too thin on top to linish back as for you brazing im not confident they will survive the kiln process but welding works great .
Thanks for the comments Welding is not a problem, I'm currently working at a welding supplier / distributor Will revert to PM
Is there a ballpark price bracket for the enamelling of Tilley hoods? I know it probably depends on condition, but it would be useful to know when considering projects/purchases?