[JLMounce]

4l60 needs a pretty pricey BOP bellhousing (not just an adapter plate) because it is designed for a passenger side mount starter. Once you get that sorted, the install isn't any different than a 4l80e. With the F-Body cars, you usually need to get banjo fittings for the cooler lines and you might need a BFH to persuade the tunnel in a spot.

Either the 4l60 or a 700r4 is probably a decent fit for this car given it's power. The steep first gear is going to help motivate the car a bit better out of the whole and make it feel more lively.

The 200r4 if you can fine one tends to not need the extras of the more modern transmissions. It already has a BOP bolt pattern and typically bolts right up to the factory cross member. I wouldn't call it "easier to install" than any of the other transmissions, it just doesn't require an adapter plate and sometimes a crossmember. The gear spread of the 200r4 is pretty nice for most performance applications. I think you'd want a 3.55 rear gear with a 200r4 though. That gets your starting line ratio closer to the 700/4l60 with a 3.42 and because the overdrive is taller, you cruise about the same on the highway.

That leaves the 4l80. It's a great transmission, but it's shallow gearing and short final drive isn't going to wake up the car as much as the other transmissions and frankly, you don't need it's size and strength here.

If this was my car and I was doing the buying, I'd probably be after a 700r4. It's readily available, would work in your power range without any fuss, and provides the best gearing for a car that isn't a power house. If you ever decide to upgrade your engine and push closer to 400hp. Do a couple of the known upgrades like a beast shell and input shaft. As it sits though the 700 would live just fine behind your current engine.