The large fuel hose is from a Mustang if memory serves. Someone with a Contemporary manual can give you the part number. The supplied tank with the kit was a 69 Camero unit with the stock sender. Not much you can do with it.
These guys make super senders, cut to fit your tank and gauge.
http://www.centroidproducts.com/
If the tank has'nt been further modified by venting the very top of the tank as installed, you will never be able to fill it more than about 60%. This was commonly not done.
Former #3140 builder