It's been a while but I recall that I needed to use the 5ME throttle body since the TPS from the 5ME did not fit 6MGE (which I presume has the same TPS as the 5MGE).
I had to change one heater hose and the upper radiator hose. I used an upper radiator hose from an RA40 Celica (perfect fit for my application, MA46).
I had to muck around with my throttle linkages as the throttle body is located in a slightly different position to the old 5ME. Probably not a issue for you; I assume an MX73 already has a cable throttle.
Not sure if the exhaust manifold will line-up with the existing exhaust. I had to change the section from the manifold to the cat. convertor.