Sprag also replaced not long ago, and it's definitely not that kind of sound. It actually struggles to turn, like strains for a few seconds before finally making a rotation. I'll get video later today.
Tested battery, cables and load, and even at one point tried directly jumping the starter itself with a big car battery, all with the same results. It's almost like it's partially seized, if that's a thing. Compression's within range too. Ugh, driving me crazy! Especially that it ran fine until I stopped and parked and then tried to restart.
Would any kind of cam timing/timing chain/tensioner issue possibly cause this?