6 (six) hours for an experienced mechanic.
Cost for a shop, as DayTrepper said, $700-$1500.
Parts for the kits, depending where you live, 200-500 in the US, Canada, 200-1200.
If you never timed an engine before, don't attempt this job on your own. The 3.X motors are a cake walk to learn. These 2.7's are dual over head cam'd, so you also have two cams on each side that have to be timed perfectly to a sprocket, on both sides, than you can time the engine via the main chain.
Just doing the water pump, you don't have to worry about secondary chains, sprokets etc. But we've seen time and time again, when doing the pump on these engines, your best doing the chains, sprockets, guides, tensioner etc.. Ultimately, it'll be a new engine and last another trillion years, until the next interval. Everything needed is offered as a kit, with the pump.
Additionally, a 3rd party makes a stop block for these motors, which in the event of pump failure doesn't let the engine destroy itself by skipping time due to lack of oil pressure to stimulate the primary tensioner.
Ultimately in that situation, most people are unaware of what is happening, and further operation will flush lubricants from the bearings, and we now arrive at crank and rod bearing knocking in the most suaver cases.
More or less a crack course what is, the 2.7. Great motor, impossible to kill. As long as that water pump doesn't get ya! Trust me, I know. We've run these little guy's dry of oil and raced them down the quarter mile. Never hurt them a bit. I won't explain the lack of oil though, for my co-workers sake. The idiot.