How do you test an electronic control unit?

I'm a little biased since I'm the one that sells the kits. :-)
But, hell yea HEI makes a big difference in the way the car starts and runs.

This is my website for the HEI kits. www.classichei.com
You would need the complete kit without the distributor.

The "ready to run" distributors and the HEI kits we sell use about the same changes in wiring of the original system, but the HEI kits use your existing distributor.

The "ready to run" distributors still need a E-coil to be HEI, so add that to the costs if you go that route.

Our kits come with the E-coil all prewired for you.