Clankety Clank low oil pressure (I think?)

[Spline64]

Hello all,

Sure hope someone can diagnose the sound I am hearing from my truck

First off, I did not install the current engine in the truck. Bought it with no knowledge of any work done before I got it. What I do know is they took out the 454 and hopped up a 350 with cam (not sure if rad or mild) and mounted to the existing tranny.

I am going to get a crate engine to return to 454 status in Feb (tax time whoo!) but I need your help to get there as I believe I am running on borrowed time and want to make sure I am not going in the wrong direction.

Problem:
When the engine warms up, at idle in gear when you start from a stop and give power, the engine will make a clankety sound like someone looking for their favorite iron skillet buried in an entire cupboard of the same.

What I don't get is sometimes (some days) the sound is much more pronounced then others. It also (sometimes) makes more noise when turning to the right.

I have tried different oil weights, engine treatments and such. Doesn't seem to matter. However, it will NEVER do it after initial start when cold until it is warmed up. Does clank when cold right after starting but only lasts for a couple of seconds which I can understand. I can run for a good 10 minutes before I hear it again after a start when the engine is cold.

I have replaced the the u-joints as they went bad just in case. Problem remains.

Any ideas?

thanks for the time,
Spline64