Battery draining overnight

Meaning you have a closed cir somewhere.

Open cir does not conduct electricity

Be sure you closed your doors before that test.

What ignition system do you have? MSD 6AL
The wiring harnesses you used are they OEM type or " universal"? OEM type from m&h

Are you sure the key is in the off position? Some times a key / lock gets so worn that you can remove the key in other than the off position. New

If you wired the field to a full time on wire that would drain the batt fast.