If $\text{Byron}=74$, then $\text{Shelly}$ is equal to:

Let us evaluate the sum of the positional values of the letters in the English alphabet ($A=1,B=2,\dots ,Z=26$):
For Byron:

$$\text{B}=2$$

$$\text{Y}=25$$

$$\text{R}=18$$

$$\text{O}=15$$

$$\text{N}=14$$

$$\text{Sum}=2+25+18+15+14=74$$

Applying the exact same coding rule to Shelly:

$$\text{S}=19$$

$$\text{H}=8$$

$$\text{E}=5$$

$$\text{L}=12$$

$$\text{L}=12$$

$$\text{Y}=25$$

$$\text{Sum}=19+8+5+12+12+25=81$$