[1985 CCX]

Nick is right on the money! Need to define your interior 1st.
Correct interior will start at:
Wilton wool carpets will cost at least $1000
Smiths $1000
Seats (good ones with tubular steel frame) another $1200 tracks an additonal $150
Door/dash leather $250
Steering wheel $500 for a correct one
Lucas Switchs $250
Correct Stick and ring/boot $250
Assorted Stainless hardware $150
Correct mirror $150
Correct ebrake $200
see where I am going, this is with your sweat equity and it is easily >$5000 before you start. This assumes you can source the right parts while in the build. A Lucas #104 mirror can take time to find as will many "correct" parts. Using Autometer, low Q seats, carpet from Home depot and MG steering wheel and you will be done for less than a G. Like anything in life, and Cobras, the variation is endless.

Best on your quest!