Biggie had a few more direct lines in an intro to Long Kiss Goodnight that got taken out at some point. If you look hard enough, you might be able to locate it.
Regardless, Long Kiss Goodnight definitely was made after Pac's death (Big references his car accident with Lil Cease), and Long Kiss Goodnight has disses to Pac that are about as explicit as one can get without naming names. "when my men bust, you just move with such stamina. slugs missed ya, i ain't mad atcha."
Not to mention Puffy's outro.
If Biggie had put out a diss track on Pac like Drop A Gem On Em (which came out after Pac's death but was clearly made before his death), it would have been no big deal. But being quiet like a churchmouse until Pac died and then making disses was pathetic.