The 36/68 issue is a case of 36 is the exit number NB, but 68 is SB. I can make the change, but is there other precedent for this?
I-840 in NC is one recent one that rings a bell where I-73 leaves it.
Pretty much, if the route has exit numbers of it's own beyond an interchange, and has a number in that chain posted where another routes numbering scheme starts/ends, we always use the posted number for the route of the file.
If they had used I-580's number 36 both ways, then that 36(580) label would have been acceptable. But since SB used US-395's number 68, that gains the priority in US-395's file, while I-580's file keeps using the 36.