Hi Lou,
Thanks for your post, The 1964 Falcon Original Monte Carlo Rallye cars had 102ltr capacity, approx 60 ltrs in the OEM tank and 42 ltrs in another tank which was mounted in Boot/trunk just above the diff or thereabouts. So I will create the same but the 42ltr tank will be a race fuel cell to comply with rules. If I run full OEM upholstery I dont think I need a rear Firewall, But I have also fabricated some .7mm aluminum plates to screw in behind the back seat which will seal off the area if required.
The original tank will remain (it has been restored and Tank sealed)
Cheers