“The oil pump gear was in the oil pan.” Are you referring to the oil pump sprocket on which the oil pump chain rides? Or are you refereeing to one of the internal “gears” from inside the oil pump? Did the oil pump come apart or the chain drive which turns it?

“The chain guide, that appears to have been cast into the block, was snapped off and in the bottom of the pan. It put a small hole in the front of the block that includes about 1/4" radius of the front main seal hole. This is where the oil leaked out.”

I assume you are talking about the area directly behind the harmonic balancer? It sounds like the damage is actually to the timing case cover, which is where the front main seal is located not the engine’s block. That is a considerably less than catastrophic issue than a hole in the block. The single row oil pump chain has been destroyed? Or the double row cam/IP drive timing chain?

If you can figure out the size of the two bolts you found that would help figure out where they cam from.

You may simply need a new oil pump chain/sprocket/bolt/tensioner/spring and a timing case cover maybe an oil pump if that has been damaged.

I don't know that the engine will absolutely need to be pulled although you might want to eventually. You’d have to take the timing case cover off to get a look inside and see what might have actually happened. With the oil pan off, you would need to pull the pulley/balancer off the crank, then remove the two 8 mm allen head bolts at the front of the cylinder head's timing chain case opening, then you can with a razor blade seperate the head gasket and slide the timinig case cover off.

If you get to that point and decide to repair what you’ve got, I’ve got most of those parts from a 91 350SD 603.971 engine. Good luck!