Go ahead with older equipment made more than 10 years ago.
Back then, maybe where prices were similar between units worldwide, it has always been easier for manufacturers of some higher priced equipment to use transformers with a primary 115-0-115v and depending on connections of this tap, can easily work with voltages of 115v or 230v.
This has changed somewhat quite a number of years ago, so to protect the revenues of your dealers. Equipment shipped as 0-230v or 0-115v transformer cannot be rewired.
Changing or customising a similar transformer can be done with a change in the sonics for the better or worst.
Back then, maybe where prices were similar between units worldwide, it has always been easier for manufacturers of some higher priced equipment to use transformers with a primary 115-0-115v and depending on connections of this tap, can easily work with voltages of 115v or 230v.
This has changed somewhat quite a number of years ago, so to protect the revenues of your dealers. Equipment shipped as 0-230v or 0-115v transformer cannot be rewired.
Changing or customising a similar transformer can be done with a change in the sonics for the better or worst.