It may be salvageable, however it will require a full rebuild which can be very expensive.
The only thing that will fix it permanentely is either a rebuild or a replacement engine.
Depending on where you go, you could be looking in the range of $2500 to $5000 for an engine swap(including engine).
A rebuild will be in that range, possibly slightly higher; however, the engine should be like new.
The V6 option will require a lot more labour and parts to make it work.