I ran some 150mm RLT Tis with a Nukeproof headset, external (+15mm) bottom cup, when I got the frame as I had the forks already.
The angles were OK but it was soon obvious that the frame needed something stiffer/bigger.
Went to 170mm Lyrik RC2DH. With the same external cup, the forks were 26mm longer. Great on straight trucking fast DHs but was a bit slack for general trail blasting, the front wheel felt a bit ‘floppy’ on climbs, steering out of ruts at slow speed etc. and it just wasn’t quite responsive enough for me.
I stuck in a Hope internal bottom cup, which dropped about 15mm off the stack and it feels great now, a very noticable difference.
The cool thing with a 44mm head tube is if you opt for a straight steerer and travel adjust fork (internal or external) then you can mess about with travel and cups to get it riding how you want. Tapered steerer forks limits you to external bottom cup though.