I have incountered the mouse thing myself on my 70 Mustang after lketting it sit for about 12 years unstartedd foir about 2 years stored in my friends barn.

Ford didnt change over to 14mm plugs untill a much later dat than 70 on 302s
Except for boss 302, 351Cs and 429 super cobra jet. Cant remember exactly what year they changed other engines.