Could I compute the norm of the orientations after simulating the full source maps?
No. With 214 signals, you can simulate 214 dipoles.
In the screen captures above, you have select 214 scouts, each of them requiring 3 values (x,y,z) => 642 dipoles. Therefore you need 642 signals.
One simple option to obtain these 642 signals:
When extracting the scout times series, do NOT the option "Unconstrained sources: norm of the three orientations". This will save 214 * 3 signals, in the correct order, just what you need.