Yes, its true. Its better to replace the engine than to build the engine because mechanics capable of rebuilding a Pajero engine are very rare.
On the other hand, let me share my experience with you.... when i bought my Pajero Gen-2 2.5 TDi, its engine was rebuilt and its been almost 02 years, i guess, and there is no blow at all and the performance plus fuel economy is awesome. Means whoever built its engine was a Pajero expert plus the previous owner spared no expense in rebuilding the engine with Mitsubishi genuine parts.
As far as the availability of parts is concerned, thats a LIE! Parts (new and kabli) are easily available at Ihata Mithu Khan, Gawalmandi and Astabal in Rawalpindi. Cost? I cant compare cuz i dont have any experience with TLC or any other brand cuz this is my first ever 4x4 and i love it. But in my opinion, parts are not that expensive.
The only issue with Pajeros, i guess, is the resale. But whoever buys doesnt think about selling it... Its a KEEPER!