Potential project Barracuda

I think I'm leaning towards tackling it pending further climbing around under the car, double checking the front end, and getting a second set of eyes on it in person for a sanity check. I'll poke around for the information myself, too, but any suggestions appreciated for a 300ish+ horsepower drivetrain that will fit easily (no firewall/engine bay cutting, stock engine mount locations a plus). Manual transmission would be preferred but open to decent autos. There is a clutch pedal assembly in the car for its current three-on-the-tree but I'm not sure if that really puts me ahead at all versus the auto probably being easier. It'd be a hole in the floor either way. If there's a common limited slip rearend that fits this car well that would also be good to know.