I have gotten help about speaker/ electric systems here before and now I'm ready to work on the engine. I have a couple questions:

1. The engine vibrates quite a bit, what kind of tuning could I do without any special tools?

2. More down the road, what kind of things could I do/get done to get a little more power out of it for about $600?

The car is a '70 Dart with about 110,000, its my first car and first foray into mechanical work on a car (except for changing the timing belt on a '91 LeBaron).

You could use some of the money to buy "special" tools, like a timing light, vacuum gage, and a tach...Yeah, and a compression gage too.
That way you can get more out of what you have already,
and when you get fancy parts, you can make them work as they should too.

Someone will say you should get a FACTORY service manual too, so add that to your list as well.

Good luck!