While I don't have one to give you for free.
www.heatercores4u.com Then go to Buick Electra under the GM section and look at 2-223.
Now I'm not sure but I think even the Abyss couldn't beat that one. And it's a whole lot less money. Even with shipping it I think you'd save.
Much as I was first interested in the Abyss or a double sized BIE at one time, this is one that is now high on my possibles list.
There is another one under the imported trucks section that is even more interesting, except it will require a bit of torch work modding the inlet/outlets to work.