Boy!! Would I like to fix cars in your neighborhood.
The labor by MB time guide dated 02/15/98 op code 01-5760 Cyl head - Single R&R 6.5hrs for 103 motor and 8.8 for 104 motor. MB dealers nor anyone else are held to those times for customer pay. Also extra clean-up time could be required, more of the front timing cover (lower) may need to be delt with once inside and parts can really vary. The belt system has to come apart. It is appropriate to save labor and do marginal things that will be uncovered. But tentioners at dealers are $248 (or who knows) so overall pricing will depend.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician