Would any of these make a big improvement or feel in performance?

Accel Ignition Coil
Jet Chips Throttle Body Airfoil
Hypertech Distributor Cap And Rotor Kit
Jet Chips Throttle Body Spacer

 

throttle body spacer is useless. Seach and you will see.
cap/rotor. Just find one locally with brass terminals.
foil/coil are fine for first mods. Easy bolt on. Will you actually see a difference? who knows. But I would go with a hypertech coil, or msd. They are higher voltage then accel IIRC.

 

Can't tell ya from personal expirnece Yet! but I've been reading and searching this forum for almost a year preparing to do my 350 tpi build and swap this summer. So to save you some days/weeks of reading from what I hear, best performance without tearing into the motor comes from improving your cars airflow. The TPI is like having an asthmatic run a race it just doesn't breath enough especailly as you get the Rev's up. Watch the for sale section and pickup a better intake like i did, then maybe some runners, and then free up the exhaust.... As long as the parts you listed are operating fine I would work on the anemic intake and restrictive exhaust to get some performance.... my 2c

 

None of the parts you listed will do anything significant to your car. The stock type ignition components work very well. I have never seen a high performance HEI coil increase power over a properly working HEI coil. Also there is really nothing special about any high cost cap and rotor. As long as it has brass terminals it is good. Throttle body spacers are garbage. The air foil is proven to add flow capability to the stock throttle body but usually does not add noticable power.
I would spend the money on exhaust.