No, he did not. You may have assumed it but "40" has not been mentioned until your post #13.
This is the 40-/55-Tech Forum. The title of the thread only mentions 2F. You asked "why would you". Which leaves the 55 Loophole.
I am generally of the opinion that the old parts when rebuilt can be better than the new parts are new. Stuff like engines and carbs and clutch cylinders. I think more attention is paid to a rebuild and the parts and skill going into it. Certainly, there are wear items that should be replaced, like radiator cores. That's why there are radiator shops. That's what they do and they're good at it. Sometimes, I think, the new OEM metal is not as thick and robust as the old metal. Things like oilpans and fenders. I wonder if the new OEM radiators are made of the same sturdy stuff as the 50 year olds are.
Why would anyone buy a new radiator? Because it's easier, cheaper, faster? OK, what about better?
There's more than one way to build a LandCruiser, thank goodness, and questions like asking why one would do anything different from you when one has already done that with good results, irks me.