In big twins the 88 represents the displacement of the standard engine in cubic inches or commonly rounded up to 1450 cc.
The MOCO released a 95 cubic inch upgrade kit to increase the displacement to 1,550 cc.
The Twin Cam 96 is approximately 1,584 cc.
The MOCO has released 103-cubic-inch (1,688 cc) and 110-cubic-inch (1,803 cc) kits for the TC96.
The Evo is the 1340 engine.