Battery Relocation Kits
I cannot recommend a kit because I do not think the kits are worth a crap; most have too small cable and they give you a ford solenoid which IMO you do not need.
I have over $50K in my Cuda so I know what you are talking about. You can easily put this together yourself and have a MUCH better system. First, you need good cable; in past years people used 1/0 gage welding cable (which works well and is plentiful). On my Cuda I used Accel Lightening Cable which is 1 gage but is very conductive and comes in red or black.
Outside of the cable, you need a battery mount (lots of those on the market or make your own). I like to install a battery disconnect near the battery that uses a switch (like toggle switch). Run the cable from the battery to the same place it would be as if the battery was up front UNLESS you are racing the car and then you will need a solenoid to disconnect the alternator from the system.