I've decided to modify the design to use the TM4C1294 series MCU. It has essentially the same feature as the MSP432, but with a higher clock speed and it is currently in-stock at multiple suppliers.
The CPU clock speed is nominally rated for 120MHz, but I have so far seen no issues overclocking it to 125 MHz to get a clean 8ns of timer resolution. The 32-bit timers also seem to have no issue operating at 125 MHz.
I've added an e-ink display to the design for debug and status purposes, and also implemented DHCP and NTP.