Well if your 80 240 is like ours, you have the small unpainted aluminum Oil Cooler. Both of the hoses connect to the bottom. I don`t know how the Cooler would attach to the Turbo Radiator. it would be best to source a Turbo Oil Cooler from PNP. they are around $20.
The Turbo Cooler is attached to the Radiator top and bottom with a bracket and one bolt. ( one bracket top and one on the bottom, each with their bolt)
So your 240 hoses would not work, unless you can figure out how to attach the 240`s Cooler.
Start looking at other peoples 300D`s at how the expansion tank is mounted. you might be able to remove some brackets from a parts car, or even make some.
You will need the hose from the Expansion tank to the bottom of the Radiator.
If you decide to use a Turbo cooler, then there is the hose problem, buy new, source some used ones. or do as mach4 did with his SL Diesel swap.
http://www.peachparts.com/shopforum/diesel-discussion/320390-oil-cooler-lines-2.html
These are some ideas.
Another option is to source another 240D Radiator, and sell the Turbo one. I think this would be the cheaper way to go.
Only you know how you want your car to look..........However, if you decide to swap in a 617.952 engine, then the radiator and expansion tank is already waiting for it.
Charlie