Clearance between header and ground ???? 1971 A Body

I have a brand new garage. Amish built with expensive upgrades for hurricane protection to satisfy township inspector. The floor of my 14x36 is 12" (1 foot) from the ground. I must build a ramp and plan to do so with pressure treated lumber. My 71 Demon is stored in a farmers pole barn 12 miles away. Can anyone tell me the ground clearance of their A bodies with a small block and the typical low hanging headers? I also need the clearance of an A Body with Doug Thorley or TTI Headers. With the ground clearance numbers- wheel base measurement and height of floor I can calculate the length of my ramp.

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