Connecting chest and head voice (mixed voice) in clean singing and false chord modulation ("grit/rasp") works rather well for me. Pitched false chord screams work fine both in the chest and head register, but I have a hard time connecting both placements through the passagio region. So I'm looking for tips and exercises to address the problem.
I'm not very skilled at pitched screaming, especially not with false chord growls, but the general way to improve continuity over your passagio is to do scale-type exercises where you practice (over multiple sessions) singing higher and higher in chest voice, and lower and lower in head voice. Over time, you will get a feel for when you need to shift mechanisms such that you keep your tone consistent throughout.
Alternately, I find personally that I can better control a sense of pitch using fry screams, so that's what I've been working on lately.
Standard disclaimer: don't attempt any harsh vocal styles without a vocal coach. While these techniques when done correctly are safe and can be maintained throughout a long career, doing them incorrectly can lead to serious damage to your voice and other sensitive tissues.