No, the SPA did not merge with APS, though many of us held membership in both organizations. Mismanagement of the SPA Sales Department led to insolvency. One of the biggest creditors, Herman Herst, Jr. threatened to sue and the organization went into a form of bankruptcy leaving most of the sellers in the Sales Department with losses to some degree.
The SPA Journal was their monthly publication. .
Thanks for the correction, jarnick. A little research jogged my memory that The Stamp Herald was the journal of the original Southern Philatelic Association.