Ritchtea
I'm in the Uk and have the instructions, if you need them send me your address by e-mail and I will post you a photostat of them.
As to the tank, get hold of a Graupner Extra 300L Leki tank this is deeper on the bottom and fits through the firewall after opening up the hole have a look at the thread "Retractaball undercarridge installation in a RTF" for a pic where I have detailed a retract installation in a Seagull PC9.
Mike