The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  1  1  1  1  1  1  0  1  1  1  1  1  1  1  1  3  1  1  3  1  1  3  1  1  1  1 3a  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  0  1
 0  1  1  a 7a+7 8a+4 3a+5 8a+5 8a a+5  0 a+5 8a  a 8a+5 3a+7 7a+7 8a+4 3a+5  1  0 8a+5 a+5 8a 8a+4  a 3a+5 7a+7 a+8 3a+7  3  1 6a+5 a+7 3a+7 2a+5 a+3 6a+5 3a 4a+3  1 6a+7 a+7  1 8a+7 a+6  1 a+8 8a+3 2a+5 4a+8  1 8a+3 6a+5  5 a+8 2a+8 8a+7 8a+3  7 2a+7 3a+5 5a 4a+8 7a+3  a a+6 7a a+8 5a+3  1  0
 0  0 3a+6  0 3a+6  3 6a+6 6a+6  6 3a 3a+6 3a  3  0 6a 6a+3 6a+6  6 6a+3  0 6a 6a+3 6a 6a+3  6 3a 3a+3 6a 3a+6 3a  3 3a+3  0 6a+6  0 6a+3  6  3 3a 6a  6  0  3 3a+3 6a 6a+6 6a+6 6a 3a+3  3 6a 3a  6  0 3a+3 3a 3a+6 6a+3  0  3  6  0 6a+6 6a+6 6a+3 3a+6 3a 6a+6  0 6a+6 6a+6  3
 0  0  0  3 3a+6 3a+6  3 3a  3 3a+3 6a 6a+6 6a 3a 3a+3 3a+6  0 6a+3 3a 6a+3 6a+6 6a+6  6 6a+3 3a  3  3 6a 3a  0  0 6a+6 6a+6  6 6a  6 6a+6 6a+3 3a 3a+6  6 6a+6  6 3a  0 6a+6 6a+3 3a  6 3a+3 6a+3 6a+3  6 6a 6a  6  3  0  3  3 3a+3  6 3a+6  3  0  0 3a+3 3a+3  0 6a  0 6a

generates a code of length 72 over GR(81,9) who´s minimum homogenous weight is 540.

Homogenous weight enumerator: w(x)=1x^0+152x^540+72x^546+648x^548+1496x^549+720x^550+648x^554+5184x^555+8712x^557+4616x^558+4968x^559+4536x^563+22896x^564+24408x^566+10632x^567+9936x^568+18144x^572+78336x^573+62424x^575+21584x^576+20664x^577+29160x^581+103464x^582+61272x^584+18768x^585+16200x^586+616x^594+400x^603+352x^612+248x^621+112x^630+72x^639

The gray image is a code over GF(9) with n=648, k=6 and d=540.
This code was found by Heurico 1.16 in 42.1 seconds.