<edit> Sorry, misread your original post and I am no help on the FW mounted cooler.
take a look at the showplanes mount. It mounts off the engine mount on the right hand side, but you'll need to make different lines I think.
I have one for my 7A with a 390 that I'll be installing as soon as I get the new engine mount from Vans. I mocked it up on my original mount and it fits quite well (hope it fits the new mount) and supports a large cooler easily.