Quite a few Stern SAM games moved from the square speaker holes to the round. AC/DC, Metallica, Iron Man. Some mods work on both while others are square / round specific to varying degrees.

I would say it is safe to say the amp head decal with the square holes will not work (or at least look correct) on the round hole panel. The round hole design can be found here:

https://pinside.com/pinball/market/shops/1084-pinball-pimp/01798-ac-dc-amp-metallica-vault-kiss-pinball-speaker-grill-decal

I may be able to help you with speaker light or speaker acrylic compatibility questions you have, if you show what you have bought.

Doug (SpeakerLightKits.com)

Well, if they are the designs that I had made (since the speakers holes changed to round), they should work in either the square or round holes. If they were made before the change to the round holes.....there may be a little bit of the designs frame that can be seen at the top, left and right most parts of the circles.

Doug (SpeakerLightKits.com)

round hole (resized).jpg

square hole (resized).jpg