Good day!!
I had a thread with my 2004 N62 rebuild on here with pictures, but photobucket destroyed that when they got rid of free hosting...
I'll see if I can put some on here directly for you... I also try to do a write up on it in the near future...
From my pictures, you MIGHT be able to do the guides with the heads installed... The lower cover has bolts that go thru a casting for the cylinder head, but they aren't the main head bolts used to hold compression. I took the chain cover off the front of the block with the heads on to seal the water passage better. I'll do a little detailed posting here with pictures in a second... I have to upload them and attach them...
Here is a shot (upside down) of the new guides with chains... Three have bolts that hold them on... There is also one that doesn't make things easy...
****I just remembered about the alternator mounting bracket... It extends around the front of the lower timing guide and down the side of the motor... That needs to be removed in order to get the front cover off... The front diff needs to be removed to get to the lower rear bolt holding that bracket on the block...*****
Here is a bad shot of the lower guide removed with the heads installed... You might be able to get the three guides out, but the last one needs to come straight out from the block... I think it will hit the head casting before it clears the pin...
If you pull the vanos units off, you can get access to the chain easily... You don't have to loosen the cam caps like I have done here for the exhaust side... That bolt on the lower area of the head is holding the top of the guide in place...
Here is the bolt that holds the guide on...
So, it would be best to remove the heads, but I personally don't think it is a requirement... The oil pans need to be loose to get the front cover in without damaging the gasket...
Let me know if you need more pictures of something specific... I'll post them up...
Cheers!!