if the Leg waggie is your first Suby project, beware the slippry slope of swappage.
It all sounds so simple. "Drop in a stock WRX motor." Then it's NOT so simple--options abound, as do "informed" opinions. "No, turbo a 1.8." " No no turbo the 2.2, they're bombproof blocks": etc etc.
Unless you can realistically tackle such a project with your own time and tools, expect to pay in the neighborhood of $3000 to $4000 for a well done swap of a WRX motor into your Leg. Expect substantial downtime while the needed fiddly bits of wiring, engine controls, etc get sussed out. Commute to Boston area to get the work done @ Dent Sport Garage, East Coast Swappers, etc. Be ready to apply more money and suffer more downtime while the bugs get worked out afterward.
Or, you can just opt for a well used 02-03 WRX wag and start with mild mods--it already has the good motor, bigger brakes, decent suspension, limited slip diff, etc. All of which would be more projects$$$ AFTER you paid big bucks to drop a WRX motor in your current wagon.
Swaps can be done, no doubt, (and there are owners of many swapped cars on this board to prove it) but the associated engineering and R&D getting the car to run right and then update brakes suspension tires etc to match the new motor's power can be more than you bargained for.
The question often comes down to, "WOuld you rather enjoy WORKING on the swapped car, or DRIVING it?"