You can turbocharge them with some imagination. I remember reading that the internals are overbuilt and its an all gear driven engine (no timing belts like the later 2.3 SOHC) and has a cast iron head.

Also heard that its in fact a mazda engine not perkins (built under licence or something). Not sure exactly, mayby its a mutt of some sort, but it will be underpowered in stock form no matter what if is if there is no turbo.

We've got a ranger with the later 2.3 TD and it has potential for more than 86 Hp if you have the time and some money to build them up. New head bolts are not necessary.