I would've said it was half Tarantula (body) and half Scorpion (legs) with a Goliath turret thrown on top for good measure. But that's no problem. Draw from reference, whether they be other mechs or real world machines. The more reference you soak up, the greater your internal knowledge will be and the more you can start to make the basis less obvious. Take a bit from this, bit from that, and throw on some of your own creativity and people won't be able to recognize the influences (including yourself, since many times a person pulls from other sources without realizing it).