I will plan to replace C20 and C21 with the below parts from DigiKey which have a temp code of XF5 and align with what SAMS specifies for replacements:
As for the SAMS test point D, that correlates to the Zenith Service Manual test point G. This test point is only used to feed the signal generator in as part of 41.25 trap alignment, for the remining IF alignment steps this test point is unused with nothing connecting to it. Before I order I will double check parts in the IF circuit. I also gambled and purchased on Ebay two claimed NOS 6EJ7 tubes. Thank you, Brad.