Work yes, but still very possible. The interlock loop (two wires) is fairly easy to change, I’ve done it on the bench many time (the R is quite a bit simpler). My biggest concern is the way the firmware recognizes the type of pack installed and then adjusts the motor control accordingly. It might mean that an original R bike might over stress an A pack or an original A bike might underutilize the capability of the R pack. I’d need to become more educated on the software to be 100% sure how the system would react. But it would run for sure. Alta made other changes to the R pack bus bars to reduce voltage drop but nothing that can’t be done as good or better with the right HV connector/leads, etc.