Install all 4 cams in the gearcase with the pinion gear removed.
Use a fair amount of assembly lube in the bushings and in the gear teeth.
Rotate them by hand and make sure they all spin freely without binding.

Then, install all 4 cams in the cam cover and make sure they spin freely without binding.

Test fitting cams in the cam cover 1)

Test fitting cams with the cam cover installed 2)