Re: 2007 Focus
How are your welding skills? You'll need a hum to accommodate the drive shaft, a revamping of the front end to support an inline engine as well a rear differential. Space for the tranny at the fire wall and in the engine compartment for what ever block you use. You might need to re-enforce the springs all the way around for the added weight. There's quite a bit of planning for this, how big of an engine are you looking at?
Prius repellant, just add gas.