I have had much experience with the 103 valve job and here is my advise. If the top end is not making any ticking sounds, and you feel comfortable taking the cylinder head off by yourself, do it!
1. number the tops of the rocker assy's before you remove them.
2. when you remove the rocker assy's, be sure not to loose the adjustment shim located just under the lifter.
3. when you get the rocker assy's off just submerge them in a small bucket filled with new oil this will protect the lifters.
4. MOST IMPORTANT!!! Take the head to someone who is very very familiar with the job!!!!
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM