As I understand it from Reynolds and GO'D Gerald O'Donovan), 753 is 531 hardened and tempered. Using brass, spelter, bronze (all the same thing) requires a temperature above the lower critical point thus annealing the tube and making it soft. Hence is loses its strength properties.
FWIW at Ilkeston front and rear fork ends were brazed in place using brass, everything else Silver Flo 55 a cadmium free freeflowing silver rod.
Mike Mullett
Reading UK