This is apparently a FAQ when it comes to C65 emulation, and as such, the developer of Hi65 has answered it in quite a few places already.

There aren't _that_ many -- few leaked, so it's not a big array of kit. The latest ROM would be preferable, and possibly fixing any outstanding bugs in it.

Another alternative is simply to emulate the Mega65.

https://mega65.org/

This could be the chance for a rebirth for the machine and thus set the standard rather than trying to follow it.