baboracus

Hello, I recently had a mark 8 but i completely tore it apart (engine, trans, dash wiring, engine wiring, driveshaft, rear axle, radiator, ah basically everything). I'm new to this forum but i was interested in placing that set up into an 80s mustang, be it a 5.0 or the regular 2.3 models. First of, what are the differences between the 2.3 and the 5.0?? Secondly, what is required of the engine/trans and crossmember mounts, driveshaft, and rear end to enable the 4.6 to fit? The mark 8 used to get around 25 MPG so I figure in a body considerabkly lighter by about 500 lbs or so that it should be able to get 27-30 MPG with a 3.73 rear axle ratio. I'll be anxiously awaiting your input.