Just bolting everything together and assuming it's all okay is one approach that usually works and although not absolutely necessary, there can be advantages and peace of mind in a one time indexing of the bell housing to the crank. Ensuring the ZF input is centered and horizontal will all aid shifting and longevity of pilot bushing & ZF. There are offset dowels available if required and numerous YouTube generic videos on indexing a bell housing readily available.
Even on the stock setup one should set the clutch slave lever arm with 1/8" free play to avoid the throwout bearing riding on the clutch.