All you need to do is take the valve covers off and have the right tools.
The #6 cylinder could present a problem for some shops without a spring compressor tool like Kirban came up with, most likely they could find a way to do that one however, I'd ask the shop first to avoid any problems.
A pro should be able to do them in 2 hours, 2.5 tops.
Including installing the new felpro viton valve seals, and new rocker shaft buttons, and new cover gaskets, and cleaning the pushrods.
Parts are another cost item for the things listed above that could/should be done during the job.