The newer stacks will fit older SVs. There are a few guys on SVRider.com that have done it and said there was a noticeable improvement in midrange.
This is the SFV set -
This is the standard SV set -
This is the thread on SVR -
https://www.svrider.com/forum/showthread.php?t=391215 . I'll update it after I get mine installed and have some seat time with it.