ZHUHAI, China—Avic’s fighter unit is pursuing its plan to build large, high-performance business jets, despite the lack of interest among almost all of the possible foreign builders that could help it do so. Avic is in talks with suppliers for a big business jet and is displaying a model of a concept for one at Air Show China in Zhuhai this week. It is also displaying a model of what it calls a medium business jet. Israel Aerospace Industries is shaping up as a possible partner for overall development, while Honeywell could become a supplier.