Top end overhaul.

[aussie 6.9]

With my 6.9 approaching 300km and concern about running hot in the summer I was thinking of doing a top end overhaul and replacing the timing chain guides At the same time.
Who would be the best work shop to do this job?
I have rodded the radiator replaced the water pump ,thermostat ,temp sender , flushed the block, replaced the thermo fan, but in the summer it still runs up around 100c.
My 450sl used to have similar issues but worn valve guides meant I had the cylinder heads reconditioned and it now runs cool in summer and no smoke.
Any advice appreciated.
Regards Mark.

 

[Oversize]

Does the temp drop when you’re on the highway?? Might be the engine fan clutch