The V-8 will bolt right into the 66, no butchering ect.. you might want to upgrade to a V-8 Radiator too tho... My old 66 GMC had everything from a 250 I6 to an LS6 454 over the years... that 454 would literally roast a set of retreads a week... I put the most miles on a 307 while i had it.
