Will a 350 engine fit into 1998 Chevy Tracker?

No, a 350 cubic inch (5.7L) engine will absolutely not fit into a 1998 Chevy Tracker. The Tracker is a small, compact SUV, and a 350 is a very large, V8 engine. The engine bay is far too small, and there would be massive clearance issues with the firewall, suspension, and other components. You'd need extensive, and likely impossible, modifications to even attempt it.