Ideas on what's causing my click/tick/rattle noise?

Are you sure it is not an exhaust leak? Do you have a windage tray?

There is no windage tray. I will check again for an exhaust leak. I can check the top of the headers easily, the lower side not so much but I'll give it a go. I don't see any blowby that would help locate an exhaust leak and I don't hear anything using a stethoscope and hollow tube.