Well... I think I have discovered the problem... I pulled the belt and it still made the noise. I started pulling plug wires one by one and when I pulled the #3 wire the noise pretty much went away. It looks like HotRodDave is likely correct. I have to assume it's a wrist pin or rod bearing. The weird thing is the noise only occurs at certain rpms and goes away under load. I have no metal in my oil either. Pulled the plug and it looks great. I guess i am going to look for a rebuilt long block. I was looking at prices and I can get one for around $1,800. I don't think I could rebuild it myself for that, especially if the heads end up being cracked. I'm bummed...