If that's all you did and you're now having trouble. I would clean all the connections and make sure the motor is grounded. You'll see a metal ground strap on the motor that bolts thru one of the mounting bolts. Make sure where that particular bolt goes thru the strap and mount bushing that the bolt is in contact with clean metal. You can use a meter and check for continuity.
Have you had the motor apart? Pump cover off, etc?
'79 Malibu wagon, mild 355 sbc, TH350 trans, 8.5 GN rear