Assuming the hole pattern is the same format between the amused electronic and the s&g mechanical one and the bolt operation is the same, changing to the mechanical won't be a problem.
I work with group 1 locks daily. The dial ring will interchange with s&g group 1 & 2 but the actual dial and case is different between the 8400 and 8500 series group 1 locks and the 6600/6700 group 2 locks. Complete lock will interchange.
The 8500 series of group 1 locks essentially installs the same as a group 2 s&g
Unless you are worried about someone manipulating their way into your safe, stick to the group 2. It's the type that is on the vast majority of mechanical lock safes including bank vaults. Also with the group 1 locks you are limited to 1 maybe 2 dial styles. Think GSA safes and vaults.