I think we just killed the poster's dreams of a car project 
But on a more serious note, here are some suggestions on engine swap:
7A-FE. Lots of low down torque and a very linear pull to redline. A very flexible engine and with the light weight of your car of choice, can prove to be quite fun and drift happy, even at low engine and vehicle speeds. The issue is a rwd conversion on this engine is a little tricky!
4S-FE. This is a 1.8 litre RWD version of the S engine. Again lots of torque and smooth power delivery! May be very difficult to find since most of them got used in generators.
3S-FE. Even more torque!
4A-GE. Any version of these, 16 valve version might be easy to convert to rwd. I believe all of the versions may be hard to find now, especially if they are in badly used condition.
3S-GTE. Only the latest generation has a flexible power delivery, the older ones are just turbo lag and then a sudden hit of power. Don't know if that will suit a lightweight rwd car. RWD conversion is possible, but you need a robust gearbox to handle the power and torque. You will also need a stronger differential (LSD preferred) and better suspension, wheels and tyres to put all that power to the ground! (I would personally avoid this option 
). This will also be very expensive!
3S-GE Beams RWD with 6 speed manual / auto. The last version of this engine came in rwd format. High revving but seems to have plenty of torque everywhere in the rev band. This engine is for the brave and talented behind the wheel. Only problem is I am not sure it will fit the engine bay because of the size of the engine and intake manifold! Again it will not be cheap to buy.
For any engine that you purchase, you must ensure you are getting all sensors and correct wiring + ecu!
Now a request to other members to add some more engine options, especially from other brands.
I can think of a mad swap with a Honda J series v6 but I guess I am getting carried away!!!
Cheers.
