A three-phase power of $3600 \mathrm{MW}$ is to be transmitted through four identical $60-\mathrm{Hz}$ overhead transmission lines over a distance of $300 \mathrm{~km}$. Based on a preliminary design, the phase constant and surge impedance of the line are $\beta=9.46 \times 10^{-4} \mathrm{rad} / \mathrm{km}$ and $\mathrm{Z}_{\mathrm{C}}=343 \Omega$, respectively. Assuming $\mathrm{V}_{\mathrm{S}}=1.0$ per unit, $\mathrm{V}_{\mathrm{R}}=0.9$ per unit, and a power angle $\delta=36.87^{\circ}$, determine a suitable nominal voltage level in $\mathrm{kV}$, based on the practical line-loadability criteria.