Sounds like you are trying to replace the case, and manufacture something new, so you can transfer the logic board and processor. Am I close?
If you have a coolant leak - you should contact Apple Customer Relations (not a service provider), and try to get Apple to replace the case/processor. As you can see, it's a big challenge (and a big project) simply to replace the case. Standard PC items just won't work. The liquid cooling is the most critical, and without replacing the processor/cooling unit, you may just be wasting your time.
What are your plans so far?