I have an old one of these late 70s Dodge truck recovery tanks here. If it didn't have the mounting tabs as part of the tank, I could put it above the radiator. The mounting tabs want to occupy the same area as the AC compressor and the serpentine belt, it doesn't fit between the hood and the motor. if I could turn it on its side, it would fit into the hole, but then the fill cap is under the part of the hood that doesn't open, and it would only have about 1/2 of its capacity. Even if it could work sitting on its side, I think its too long to clear the closed hood wings.

Pics attached. The above 70s Dodge tank above the radiator, and with a tape measure showing the space I have. The shortest larger recovery tank I've found is 10" high.
The aluminum tank is 6 1/2" high and 4 1/2"" wide. It would fit at the very center under the part of the hood that doesn't open, but that wouldn't help much because I still couldn't add anything to it, and its still too small.

I suppose I could mount another tank like the one I already have as a secondary over flow, kind of like a recovery tank for the recovery tank, but then I would have a big batch of 3/8" coolant recovery hoses running all over the place because the radiator cap would be between the two recovery tanks. How would I run the hoses to them?