And if you just want to go the simple route, how about these thoughts:

1) Headers going back to turbo mufflers. Relatively cheap and pretty efficient. Sound mellow too.

2) A PAW cam and lifter set up. Less than $100 and is actually a Crane cam in a private label box.

3) A Unilite distributor and Accel Super Coil. I've got this setup in my 5.0 powered Jeep pickup, and it is flawless for the street.

4) Any dual plane aluminum intake.

5) An Edelbrock 500 cfm electric choke carb. I know alot of people like Holleys, but on my street cars I don't like to fiddle. You bolt Edelbrocks on and forget they are there. No fuss no muss.

6) An electric fan. It will cool better and free up some extra HP.

7) A good double roller timing chain set. I've bought house brands, and they are not accurate. Still won't cost a fortune.

8) A good set of high perf plug wires and new plugs.

9) You say you have a 3 speed. Good. thesals is right about stock c-4's going out with no warning. Been there. The 3 speed will do fine until you get more money to go to a 4 or 5 speed. I've abused the 3 speed toploader in my '27 for 14 years, and it still works great.

10) Gears. No other modification for the money will give you the seat of the pants performance as simply dropping your rear end ratio a little deeper, especially with that stick. Right now you probably have something like 3:00 gears, I would go to 3:70's in that 8 inch rear. 4;10's are too deep, in my opinion. Nice around town, but don't get on the interstate unless you like buzzing 4 grand all day.

My ex-wife had pretty much this same set up in her little '68 coupe, and it got decent fuel milage, was dependable, and ran a whole lot better than when stock. A WHOLE LOT BETTER.

The reasons I am making these particular suggestions is that you are probably going to be a little tight on money just from buying the car, so these can be done one at a time as you get more cash. By the way, put all of your old take off parts in a big box and KEEP THEM. If you ever go to sell the stang, the next guy may think it is worth a lot more money stock. (Remember all the guys who tossed stock 426 Hemi exhaust manifolds in the dumpster back in the'60's. Check the prices now)

Enjoy the mustang. The 67-68's were great drivers.