The other alternative is to find a factory G slide
The machining on FS slides is different from the machining on the G slides. FS slides can have certain new holes drilled, and other filled, and G parts installed, and it becomes a G slide. The G conversion works on a FS slide, with no machining. The alternative to this is to find a factory G slide, but it will not have 92A1 markings.
The easiest to find G slides are for the .40 caliber 96. For range use only, I've used a 96G slide with a 92 barrel and magazine, with no issues.
Finding a 92G slide will take some looking. Ask about it on the Beretta forum, and someone will eventually make you an offer.