In your shoes I'd do just what your talking about as it clearly doesn't need a complete overhaul. I'm not familiar enough with that engine to know wether it has easily removable liners or press in ones, but if it the liners are easily removed I'd replace both the piston and liner together. If the liners are pressed in them at least run a dingleberry hone through it so the new rings will seat in properly, and as you said just install one new piston.
As far as injectors and having the valves checked that's a really good idea, along with a new set of injectors (given the lack of fuel quality nowdays).As far as the bearings, I'd check and see if there is really even enough wear to bother with them. With no more hours than it has on it, the old ones shouldn't be hurt enough to bother replacing, if it was serviced regularly.