70 duster points to electronic diet and hei wiring

I got my stock mopar electronic distributor hooked up with the adapter plate and hei module. I’ve hooked up the two wires from the distributor to the hei module, but I need to complete the wiring with a positive and negative to the hei. I’m assuming just ground the negative to the engine? Where do I get the 12 v (do I reuse the one wire that fed the old points distributor? Or is there a better wire I should use for positive? Then i’ll pop it in and fire it up. If all is good i’ll Upgrade the mopar canister coil to the ecoil and bypass the ballast, but one thing at a time.