I don't believe that there is such an animal as a "stock" 1970 351W with a 4V. In '69, the 351 Windsor was available with both a 2V or 4V engine option. When the 351 Cleveland was introduced in 1970, that became the only engine supplied when the 4V option was ordered. If a 2V 351 engine option was ordered in '70, it was the luck-of-the-draw as to which engine (Windsor or Cleveland) would be supplied. Both were.
There may be rare exceptions to this, but I haven't seen one. If you have a '70 with a 351 Windsor and a 4 barrel, then it is more likely that someone switched the stock '70 2V intake manifold for a '69 4V manifold. That is what I have done.
Mountain Dew & Donuts, because breakfast is the most important meal of the day!
'66 Coupe 289 2V done for son
'70 Coupe 351W 4V (She Bear), doing for me!