Tim,
I'm currently assembling a 72 240hp 351c for my cougar. My engine is required to have .407 lift @ the valve & the 1.21 carb. The 70 uses a bigger cam and the 1.23 carb. Also, a 351W & 351C are both rated @ 250hp in 70. I have it on good info, from someone who ran this before, that my combo is quite capable of running the index.
I just need to get closer to his recipe.