I would try to get a stock or close to stock motor to start with. Find a complete one if you can, get the "Idiot's Guide," and rebuild it. Do your learning and mistake making on that motor. Even a stock motor can be pretty fun to drive, even though a stock 1600 only has about 55 hp, the cars only weigh ~1700-1800 lbs, so the power to weight ratio isn't too bad. Stock motors also respond really well to a header and a pair of dual carbs, the intake and exhaust on them are huge restrictions. You can also put in some higher ratio rockers. Do all that and you will notice a big difference. If you do all that, you will have learned a lot and can make a really informed decision on a big motor.
As for big motors, there is no right answer. The engine in my daily driver is more radical than a lot of full on drag motors and would be way too much for most people. Other people are happy with slightly modded stock motor I described above, it's totally up to you and your "style," your mechanical abilities, and your goals for the car.
