The lobe lift multiplied by the rocker arm ratio determines valve lift. The use of a 3/8 stud as opposed to a 7/16 stud is diameter, but you cannot interchange rocker arms. If you were to put 7/16 rocker arms on a 3/8 stud, you will create a lot of extra play and probably shear the stud off. If you know the valve lift and the rocker ratio, you can cross multiply to determine the change in valve lift using different rocker ratios.
Ex. 1.52 rocker with .503 lift and you change to 1.6 rockers. Multiply 1.6x.503 and divide by 1.52 and valve lift will increase to .529 by changing from 1.52 to 1.6 rocker ratio.

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