If a part is unique to the 65 than expect it will be significantly higher priced than the equivalent part on a V8 car (MB luxury tax). Repairs in the engine compartment can take significantly longer due to the limited space to work. It took the tech at my MB service department a day and a half to replace the leaking tandem pump and rodeo my car (at 19,000 miles under warranty).
Donít forget youíll need 24 new spark plugs at 50-60K miles. Intercoolors and coil packs have to come off first. Intercoolors have to be bled for at least an hour afterwards.
Iím not forecasting doom and gloom, nothing will break that canít be fixed. I just saying you have to expect repairs to cost more than a V8, in some cases significantly more. I also think your mechanic might be optimistic about what he can handle if he has never worked on a M275 or a MB with ABC before. My service department only has one tech thatís been officially trained for the M275.