Butterworth filter

Dear all

I am doing an exercise but I am stuck on this, maybe someone can help

I have designed a constant K filter with a pi network where the load is 600ohms and the cut off freq is 15kHz, now i need some help to design the circuit response showing it as a Butterworth response.

Found already the L =12.7mH and the C = 17.68nF then need some help.

Thanks.