ive finally started my project but im curious what all harnesses do i need to actually start the engine just the engine harness? and ecm? also do i need a gauge cluster for it to run id like to run as few wires as possible just to keep things clean
Yes, engine harness (with bale plug & goes to injectors, sensors, etc) and the harness from that one to the underhood fuse block. It'll also have the lead to the throttle pedal, ECM & OBDII port. You'll want both of those items as well.
You won't need the gauge cluster for the engine to run.