Spring will be full winter mountaineering conditions requiring ice ax, crampons, helmet, as well as the knowledge of how to use them (this year it was full winter conditions on Whitney Main trail well into June/July due to the heavy snow year). Williamson and Tyndall are usually the two that are linked up fyi. I found a thread from 2022 in this forum about a possible off trail route and other options that might give you more info:
http://www.whitneyzone.com/wz/ubbthreads.php/topics/59495/williamson-to-whitney-high-country-route
