great video on caster. I was led to believe that more C angle was not for high traction ( I think read from the HUDY guide) and then wondered why the pros opted for more angle. This helps! well done for the video.
Regarding B6.1 front rake, what happens if you just reduce rake in the arms, (25deg to 17.5deg) machining the aluminum bulkhead and adding a shim? The tower remains 25deg.
Less rake has two effects. Assuming you change nothing else, it reduces caster. If you compensate at the caster block, then the remaining effect is less diving under hard braking. If you're on a bumpy track, though, front rake is very important and will keep the front from bouncing all over the place.
Kind of the opposite for the front end. A larger kick-up will mean more dive under braking. This is because the weight transfers forward, so a larger kick-up will absorb more of that than if the arms were parallel with the ground (in which case you'd need a vertical weight transfer rather than a longitudinal weight transfer to make the front dive).