My 2013 Scott Specialized confirms that the only perf is 11.1 x 11.
Of course, you know that there were two different Louis Armstrong stamps at the time, but both had the same perf 11.1 x 11.
One pane featuring him alone (Scott 2982) issued on September 1, 1995 and had white denomination as shown here:

Louis Armstrong was also part of the Jazz Musicians pane (Scott 2984-92) issued on September 16, 1995 and the Louis Armstrong stamp in that series was Scott 2984 and had black denomination:
