Will the P-mags clamping force be different?
E mag do not specify their clamp torque in their installation manual.
https://www.lycoming.com/sites/default/files/60297-29.pdf
page 5.3
(11) Tighten the magneto mounting clamps to secure the magneto to the engine.
(a) Inspect to be sure the correct gasket is being used. The gasket should be circular and no part of
the gasket should extend beyond the flange of the magneto housing.
(b) If an attaching nut is removed, install a new internal tooth 5/16 lock-washer.
(c) Alternately tighten the magneto mounting clamp nuts to 8 ft.-lbs. of torque.
(d) Continue to alternately tighten both nuts, using several steps, to 17 ft.-lbs. of torque.