Plenty of posts on this subject if you do a search but from what I've gleaned, you're looking at a cylinder head rebuild/swap (valves etc.) and replace the big end bearings... could work out expensive with labour costs!
Might be worth weighing up the cost of having a good second hand lump dropped in.
The big question is this, TS or V6?
TS's with a dropped belt, you are looking at bent valves for sure. Also the big end bearings will need to be changed, do not accept the car without this being done.
Most lightly you'll need a head recon with new valve stem guides in where the damaged ones are and new valves there. Head gasket set, head bolts. Then the pistons can come out and new big end put in. You could need new pistons, but that would be very unlucky. I'd get new rings put on just because you are there and they are 11 years old and ??? Miles.
Then clean up and reassemble, with all new belts and new water pump. The new water pump is also just a good thing to do unless you know it's been done recently. Also on a TS a new variator is a good plan.
On the V6, much the same. Just 2X heads, only 1 belt and no vari. I'm not sure about the big ends on the V6.
As super164 said it might be worth looking at a replacement / reconed motor. Just get the Mech to pull the head/s to see the extent of the damage.