Never once encountered an auditor who cared about the FAS35 assumptions.
Since PVAB (fas35) and ABO (fas87) and funding target (IRS) are essentially the same concept, there should be value in having them be the same (or similar). But not required. They have different purposes, so don't overlook the documentation of the assumptions. FAS35 has been around a long time (1980), well before the concept of ABO and funding target, and well before any financial statement recognition. It is much less important now.