340 Chugging instead of Reving

I maintain your spark plugs are telling you it looks like one plane of the manifold is sucking oil, with probable vacuum leak.
The other runner, not so much.
Perhaps put a vacuum guages on it .
My mentor had me read EVERY spark plug I took out, prob a thousand.
They always tell a story .
Hope it helps

That does help and also reminds be that during initial start up, it started hard and wouldn't idle. Being a fresh build, I did t want to run it long under that condition but it was long enough to find a vacuum leak on both sides of the intake. When I replaced the gaskets I discovered that I had used LA intake gaskets and I should have used Magnum. There was just enough difference and more meat to seal them better. That partly answers to why the plugs look like that. I think I'll buy a new set so I have a fresh look at them. Also, I did a.vacuum check while adjust the carb and it appears good now. Pulling a steady 12 lbs which I thought was good with this cam.