This is a short idle video of my 400 based 512. It has a Comp retrofit roller cam and lifters in it. It does sound like diesel at idle and I just attributed it to the valve train making all that noise. I've never owned a motor with a retrofit roller setup, nor have I owned one with a stroker rotating assembly. It was recently pointed out to me the sound I'm hearing is most likely piston slap as a result of the pistons essentially being hockey pucks. Mine sounds exactly like a couple of other stroker big blocks with flat tappet cams.

That being said I don't think noise from a roller cam is going to be a concern from what you'll get from piston slap.