How do hydraulic flat tappet lifters fail?

Yes, prime it turn motor by hand or even bump it (assembled) with no spark. You got so much assembly lube on it that a few revolutions wont hurt the cam or bearings. Remote starter switch is great for this. The lifters are very easy to see with no intake on it. Hand rotating will be enough to notice if the lifters are 'rolling' in their bores.
I did mine by hand I dropped the lifters in and cranked it with a ratchet a couple revolutions.