Zesty mullet conversion

Currently have a 2013 Zesty 514 with 26" wheels but after last service Silverfish UK have said my 32's rebound adjust is buggered & no surprise parts are discontinued. Reviews said it would benefit from upgrade to 34's, so my question is:

Do I buy 26" 34's 150mm travel or get 27.5" version with 150mm or 140mm travel?

I understand there might be a risk of snapping the carbon but after 12 years of casing jumps she's not failed me yet...I just want a bit more life out of her!