doubt it is the oil pan...especially undenting it to "release pressure" The oil pan would have to be dented in pretty far to obstruct the pickup enough to prevent oil flow. I'm talking like 3.5"-4" here.
I'm betting it's your hydraulic lifters if it is coming from your head. How long have you run the motor for? Search through my "created threads" and I have a couple of videos linked up of how my motor sounded before I took it all apart again. Or search putfile.com for RB25DET and you'll find it. EDIT: here it is...
zerothread?id=179220Turns out a few of my lifters were reinstalled backwards because I'm a moron.
Otherwise it could be an exhaust leak from your manifold since the exhaust manifold studs have been notorious for breaking on RB's. That makes a kind of ticking sound as well.