from the top of the front core support to the top of the radiator cap
'67 Barracuda which should have almost the same body dimensions, give or take production tolerances...
Test Fit #1. ZERO Clearance to hood.
As checked by gently closing hood on crumpled aluminum foil.
Test Fit #2, Good fit - same '68-'69 radiator with '70 bottom tank and slightly shorter core.
5/8 to 3/4" hood clearance.
#3 Hood clearance with square top (70 up) radiator (with radiator shifted forward to provide more fan clearance).
and yes I have, or rather had, a dog. LOL.