Pi mods
Clocks
X1 (25 MHz) and X2 (19.2 MHz)
19.2 txco, 100ppb (.1ppm)
https://www.digikey.com/product-detail/en/connor-winfield/M100F-019.2M/CW783DKR-ND/3885145
or larger package
https://www.digikey.com/product-detail/en/connor-winfield/T100F-019.2M/CW757CT-ND/3757168
$10, 0.28ppm
25 MHz
$17.5
https://www.digikey.com/product-detail/en/abracon-llc/AST3TQ-T-25.000MHZ-28/535-12700-ND/5017691
Power
+5 - Two ultracaps to +5
Voltage regs
1.8v
https://www.digikey.com/product-detail/en/stmicroelectronics/LD1117V18/497-3457-5-ND/669255