Well, you could get a "U" cooler with horizontal ports, then just extend the hoses from the rail through the tunnel into the cooler. As for the tunnel extension I just build my own, do a drawing, build it rough from cardboard then I have them all laser cut and bent, I weld them up, done. I'll try to post a pic of one I just made for a cat, going from 136 to 151. Don't over think it, it's easy. I have an 01 tunnel in my shop right now, if I get some time I'll try drawing one up, no guarantee, very busy right now.
Cheers
Yea, makes it nice when you want to build something. I'm also getting my shop set up sweet too, lathe, mill, tig, rolls, brake, it's coming. If you want something built or anyone you know, drop me a email.