Measuring Challah

The obligation to take challah from a dough is when the volume is 43.2 beitzah (eggs).  According to Rav Chaim Naeh one beitzah is 1.9476877 oz.  According the Chazon Ish one beitzah is 3.3814 oz.  (Practical Talmud Dictionary, Frank)

Question: How many pounds of dough do you need to have before you are obligated to take Challah by both opinions?

Answer:

Rav Chaim Naeh:

One beitzah is 1.9476877 oz.

43.2 X 1.9476877 = 84.1401086 oz.

84.1401086 oz. / 16 = 5.25875679 lbs.

Chazon Ish:

One beitzah is 3.3814 oz.

43.2 X 3.3814 =146.0765

146.0765 / 16 = 9.12978 lbs.