The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  7  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  7  0  0  0  0  0  0  7  7 21  7 21 14 35  7 14 14 28 42 42 14 14 35 42 35  7 21 14 21  0 42 35 21 14 28 35 35  0  7 42 42 35  7  0 35 14 42 14 28 14 42 21 35  7 28  7  0 42  0  7  7 28  7 42 28  7 42 35  7 21 35 14 35 35  0  0
 0  0  7  0  0  7  7 28 35 42 14 14 35  7 42  7 21  0 42  7 28 42  0 35 14 35 42 42  0 35  0 42 14  7 14 21 42 35 21  0 28  0 35 35 21 14 28 28 35  7 28 42 14  0 14 42 28 28  0 28 28 21 28 28  0 35  0 21 28 35 42 14 21 35 14 14  0
 0  0  0  7  0 35 28 21 35 28 21 42  0 28 42 35 35 35 35 14  0 42  7 14 35  0 21 21 21 35  7 14 42 14 42 21  7  0  0 21 35 21 42 14  7  7 14 21 14 21 21  0 21  0 21  0 42 35 42  7  0 14 14  7 28  7  0  7  0 42 14 35 42  0 42 42  0
 0  0  0  0  7 35  7 14 14 35 35  0  7 14  0 21 14 42 35 42 14 28 28 14 21 42 28 21 14 14 35 21 42  7 28  7  0  0 42 28  0 14 21 42  0 28 21 14 14 35 42  7 21 35  7  0 35 28  7 35 28 14 14 42 14 28 14 35 42 28 28 42 35 21 14 28  0

generates a code of length 77 over Z49 who´s minimum homogenous weight is 420.

Homogenous weight enumerator: w(x)=1x^0+198x^420+864x^427+1356x^434+1662x^441+1788x^448+1854x^455+14406x^456+1836x^462+86436x^463+1728x^469+1698x^476+1302x^483+1122x^490+762x^497+426x^504+174x^511+24x^518+12x^532

The gray image is a code over GF(7) with n=539, k=6 and d=420.
This code was found by Heurico 1.16 in 18 seconds.