What to do with 2007 4900 WS engine

Hi Guys - I have a Western Star 2007 sitting in my shop.
It has an MBE 4000 leaking oil from head gaskets, 1.2 mil.
I pretty much replaced all the parts on the truck except engine. Had the EGR filter deleted and I put a 200,000 on it after purchasing it with 1 mil on it.
Doesn't run bad, but that oil leak is getting bad.
Nobody will give me anything for it.

Thought maybe I could place another engine in it for not too much - wishful thinking huh?

Or maybe I could fix the oil leaks and use the truck for a spare.

But I already have another one setting around I could use for a spare, a 2001 9900 with a 3406ek in it, it also has some small oil leaks.

I guess I was just wondering what you all thought about fixing the Mercedes or swapping with a Detroit or similar engine?