Report in GSTR 1- Export invoice

An Assessee who export goods not directly from india, in place of this, give purchase order to china with the terms and conditions of directly ship to kuwait, for which consideration received from kuwait towards sales or export by raising an export invoice and payment made to china towards purchase or import, in that situation, how to report in GSTR-1 about that invoice value whether under serial no 6A or 8, which is better and proper? please guide.