Will a 1994 Chevy 350 throttle body fit 2000 350?

No, a 1994 Chevy 350 throttle body will almost certainly not fit a 2000 Chevy 350. While both are 350 cubic inch engines, the design and specifications of the throttle body changed significantly over those six years. The intake manifold, and thus the throttle body mounting, are different. Even if the bolt patterns *seem* similar, the bore size (the diameter of the opening) and the electronic connections are likely incompatible. You'd run into serious issues with fitment, airflow, and possibly even engine control system malfunctions.