We would like to design DC-DC converter as per blow

Vin: 16-40VDC

Nominal Input power of DC-DC converters will be 30W and sometimes 50W max.

Time (Sec)                        Voltage

0.01              80 V

0.02              80 V

0.05              80 V

0.1                 78 V

0.2                 73 V

0.5                 62 V

1.0                 49V

3.0                 33V

7.0                 33V

Please suggest us suitable part number/ design for this.

 And please let me know any application note/ design reference to design or select the TVS diode/GDT for these kind of applications?