Intake valve seat inner diameter is one limiting factor to cyl head flow. Stock size is 1.76 in. inner dia. Take half of that, square it and multiply by pi and you get the max flow area. Also factor in the valve stem diameter 0.341" as reducing flow x-sectional area.

Then look at the ports and measure the area at the most-restrictive point. It's not the dimensions at the port opening, rather inside the port somewhere. I came up with 1.875" X 0.875" and calc'd the area of that.

Then, determine the curtain area of the valve exactly when the valve is opened sufficiently that the curtain area is equal to the port minimum x-sectional area.

What I found was that when valve lift was below 0.302, airflow was not port-size limited.

So events fpr one cycle can be segmented into four situations:

1) valve lift between 0 and 0.302"
2) valve lift between 0.302" and max
3) valve lift between max and 0.302"
4) valve lift between 0.302" and zero.

For the duration of 2), 3), cylinder filling is limited by port size relative to seat diameter; for 1), 4) it is not.

If I increase minimum port opening to 2.36 sq. in., then the port would never be limiting with respect to the valve seat inner diameter minus the valve stem diameter. That's going to be tough to do.

Want to increase that 0.302" number, seemingly, but do I really ?

When intake valve lift is zero, port velocity is slow. It opens and air velocity through port steadily increases, till it hits about 0.302", at which point it increases even more at the most restrictive point in the port. After max lift achieved, port velocity at restriction slows until 0.302" is again reached, then a further drop. The $ 64 question is - where do you want the most restrictive point in the port to be and what size do you want it to be ? My read is that the opening of the port on the head is where I want it, with a steadily increasing opening.