I am not sure what you are looking for here, but if you want a working heater, then you need to replace the core. Now, I know you know this, so....the hardest part will be finding a core. I know Modine lists one, but I don't know if it actually exists. The dealer and junk yard are your other options.

After that, go down to your parts store and ask to rent their metric set of double-jointed heater core midgets and tear into it. AFAIK, it is not a bad job, just cramped.

Good Luck,
Michael