[RichardJ]

>> Its a four prong so I assume its 30 to 12v power, 86 to solenoid green, 85 solenoid black, and 87 to the HEI? Curious though, I am getting 12volts from the solenoid to the HEI already. Is it an amperage thing? If so what kind of amperage do I need to have at a minimum?<<

For most, the actual current draw of the stock, original HEI is of little importance or at least they seem to think they know more about the HEI than Chevy.

From the horse's mouth. Spec sheet for 1975 Chevy C10-30, the first year of the HEI.

The stock, original HEI draws 2 Amps. Listed as Ignition in the first image.

For those that can't be convinced or are using a big MSD that may draw about 10 Amps then I'll look at how a relay should be wired.

Relay pin 30 is connected to 12 Volts, preferably from Junction Block near the Battery. Not the starter solenoid.

Pin 87 does go to the HEI Bat terminal.

>>86 to solenoid green, 85 solenoid black<< I'm not going to waste my time asking what that means, other than to say I hope it has nothing to do with the starter solenoid.
Pin 85 should go to ground. A short wire from pin 85 to the screw holding the relay to the fender is all that is needed. Pin 86 is connected to the control voltage (ignition switch) to turn the relay ON, when the key is in the ON or RUN position.

Sorry the wiring diagram is so small. No matter what I did to the image, the forum software miniaturized it. Hopefully you can use your browser and make it large enough to be useful.

The 12 V source for the ignition source, as with everything, starts at the battery and goes through the bulkhead connector and is still labeled 12R. 12R goes to the horn relay, the headlight switch, PART of the fuse panel and to the ignition switch. The ignition switch connects the 12R to the 12P. 12P runs back to the bulkhead connector and also feeds another PART of the fuse panel.

For those that think, punching a wire through the firewall in order to connect to the fuse panel is a good idea, I will always argue that they are spinning their wheels.
The 12P from the ignition switch, already connects the 12Volts directly to the bulkhead connector.

You don't even have to stick your head under the dash to get the 12 Volts for the ignition distributor. Remove the resistance wire from the bulkhead connector on the engine side of the firewall and run a new wire directly to the HEI or if you really must, to pin 86 of the totally unnecessary relay.

I have the Innova 3568. If it has any fault, it is that the cable can be detached from the bottom of the handle too easily. When I bought mine years ago, the upgraded version with Red rubber protectors was quite a bit more expensive. If you do consider the Innova, for myself I would consider the upgraded red model with dwell and voltmeter features. The Actron is 1/2 that, so your choice.