I've kept a 16" Tig with a 12" Jur previously without issues, they shared the tank with a similar sized Planiceps and a 20" TSN in my 240 with two very large pieces of driftwood. I've never had any aggression between my shovelnose cats unless one was small enough to be eaten by another.
FWIW also cohabbed a 28" TSN, 22" Lima, and 20" Planiceps in my 1100 and a 30" Planiceps and 13" Brachy Capa in my 480 without any problems.