96 volt pack to a 90 volt system?

hey there
this is my first post.
I found a 1991 colenta pick up, here in holland, the pack is 15 x 6volt/160Ah, 90 volt agm and it is sulfated. I need new batteries and began to think of a lithium conversion. The closest pack voltage i can find is 96 volt. Would the extra 6 volt difference fry the controller and motor?

specs : Controller - Curtis 1221
Motor - 90 Volt AC motor
11kW / 20kW (3min.)
137A / 300A (3min.)
Torque 35Nm

Is this enough info? or am I being to vague? please help with any insight, expertise or tips.

thanks mike lenis
1991 colenta in europe