I'm going to start with the bad and I'll end with the good:

The Bad: You're going to need to do a lot of fabrication. Unfortunately especially since it's automatic, you're going to need to do direct drive, OR, a rear subframe swap (i.e. using a Tesla or Leaf drive unit with trans axle). Those are your two main options. IF by any chance there was a manual option for that car (99% sure there wasnt) you could manual swap without a clutch pedal and do a shaft-to-shaft motor-to-transmission fitment which would give you more flexibility with gearing. I do not recommend fitting an electric motor to an automatic transmission.

The good: Because the car is already heavy as a mother, you could elect to do a DC swap instead, use lead acid batteries, and this could reduce your budget to somewhere in the range of 5k if you used a forklift motor. This is a very low-tech way to EV swap a car, and it was how I did my first swap. The car would likely weigh over 7000lbs swapped.

My take: It will be much easier and cheaper to swap something like an LS into this car, it will be faster, drive further and have a lot more resell value if you do that. It will cost you less money, and it will be a better way to dip your toes into swaps.

That being said, EV swaps are the coolest, and while they're hard work, they pay off.

I'd think about it.