Easiest conversion would be a K series motor. (Lots of info in the FAQ) I'm currently in the process of putting a 5K into my KE70. They can be decent motors if you do the right mods to them. There is a worked 4K for sale at the moment, may be worth having a look at.
The manual gearbox you want for a K series motor is a K50. Its a 5 speed and there are plenty around so start looking. Theres a thread i started called 5K in KE70, have a look in that there is lots of info.
For $1700 you should be able to build a decent K motor as long as you are prepared to get in there and do some work yourelf. But you could probably get close to dropping a 4age in for around $2000, so it just depends on what you want the car to do.
Goodluck.