Hello, I recently ordered a used JCM800 Model 1580 Bass Cabinet.  The seller's photos show it with one 18 inch Celestion G18Q-400 speaker.  I've learned that they were made in the 1980s-90s, and came in mutliple speaker configurations. Mine is the 1x18.  I'm assuming the cab originally came with the G18Q-400?

Would really love to know:

1. the performance specs of the G18Q speaker (Celestion.com didn't have any info)

2. whether the round port cut in the baffle of the cab is original. 

See picture below.  Thanks!