usually when no accumulator like in the pic, it already has a shift kit/trans brake/manual vb. we leave ours out in race only apps. some shift kits tell you to put it in, use/make a blocker rod. you need to do further investigation.
Manual VB yes, just a shift kit? Never that I've seen... Manual VB you can eliminate the governor & assorted other parts...
Taking a accumulator out of a fully automatic 727 allows fluid to bleed from one circuit to another..
I no longer have my fluid charts so these came from online... But it shows two gears one has fluid on both sides of the accumulator, the other only has fluid on one side... (Accumulator is on the center right of each chart) If the fluid can travel back through the accumulator two gears can apply at the same time... Bad juju...