C15 6nz identification

I bought a used c15 6nz03673, the motor was sand blasted and painted. All the data plates and tags were removed from the motor so I just have the word of the place I bought the motor from as to the serial of the motor. I've looked for numbers stamped on the block and can't find any. I've got a Miss and suspect an injector, I popped off a valve cover today to get an injector part number to make sure cat stocked them, in my #1 hole it was a 249-0709 and couldn't make anything out in #2. Is there any way for me to find out what horsepower rating my hard parts are? I have a 550 tune in the ecm

 

Ok, thank you. I'm heading in right now to get a cut out test done. I will try to get the rear cover off the head and find the cam part# if I'm opening it up for an injector. I did not get the original ecm with the engine... If I did I could verify a little more. All I have now is hearsay from where I got it.

 

I have looked for a stamp in the block, cant find one anywhere. It was the first thing I looked for when the motor arrived and I saw the data tags where missing and I have looked again and again, was hoping there may be a hidden spot they put it. Would my turbo #s verify anything?

 

This block has been sand blasted and painted with a pretty thick coat of paint. I see a flat spot on the block, pass side rear but definitely no markings, how lightly do they stamp them? Should I sand all the paint off? I haven't pulled the rear cover off the head yet to check the cam part#. I mostly want to verify I do have a 475-550. Knowing a proper serial# is also nice when ordering parts.....