Okay buddy, can't no one tell you anything.
First off when people flow test heads the usually use a rather large bore plate (4.125-4.200) as to inflate the numbers. Head manufactures have been doing this for years, as well as head shops do they can make their work look better. But since you are using a 3.875 (3.905 @ .030) then those flow numbers decrease much more than you think. When you see a pair of heads from a manufacturer that have been flow tested out to say 250cfm at .500" (4.200 bore plate), I've seen these re-flow tested for a 350 with a 4.030 bore plate and only make around 235cfm. With that much loss going from 4.200-4.030, imagine how much more loss there would be to 3.875.
Your cylinder bore makes a big difference because it is what is creating the vaccum to suck the air down into, obviously a 4.200 bore will create more vaccum than a 3.875. Increasing the valve size from 1.84-1.94 will help some but not that much, I would bet my car that your 601 heads flow tested with a 3.875 bore plate wouldn't make over say maybe 205-210 MAX at .500"
You came on this forum and asked the questions so don't get angrey because you are getting answers you don't like from people who know what they are talking about. I've seen it a hundred times, when peoples bubble gets deflated.