Hello,
Do not replace radiator with local one. If you need to replace radiator get a new one for Pajero Mini Jr. its available new and fits without any mods. Or get the current radiator serviced.
Check if compressor's bearing is ok, it wears out and makes engine heat up due to extra load. I got compressor replaced few months ago for similar heating up issue. Compressor was bad, after placement issue resolved.
You also need to install the thermostat valve back, it makes sure engine runs at optimal temperature. Recommended temperature is needle just under half mark.
Hope these tips will help you.