The overall size of the crane must not be changed. The height and reach of the loading point is to remain the same .  Original parts must remain and you are allowed additions such as corner plates, , bracing , re-enforcing etc. The maximum stress level of any component needs to be less than 75 MPa.  If you can't maintain the max. stress level under the specific level,  you need to justify it  Also you need to limit the vertical and horizontal displacement at the loading point less than 50 mm.

Create a suitable model with beam elements and perform an FEA for:

1.  Original crane arrangement

2.  Modified crane arrangement