[dsraven]

Probably nothing too special and you could likely loosen the line nuts and then unscrew the brass fitting in the block. The block will likely be threaded to a national pipe thread (check with a simple pipe fitting to see what screws in, remembering that pipe threads are tapered and naturally get tighter as the fitting screws in). Then, with that in mind, a new brass fitting could be installed in the block, on both ends, that would accept a simple, off the shelf, brake line of the same size as the original tubing. Just make sure the new fittings dont have a smaller ID than the original fittings or they will cause a restriction in flow.