What you need to consider is if you don't remove the brake/fuel lines you need to ensure that you can apply the proper corrosion prevention measures (treat-prime-paint) Make sure you cover up all your plumbing too, you don't want them full of sand.
With sandblasting it removes the factory primer, therefore it is important that you properly treat the surfaces for corrosion prevention.
The firewall and inner guards should be thick enough or have enough shape to resist deformation during sandblasting.