Rene,
The Sprague clutch is larger in the P type with a slightly beefier "cone clutch".

The splines changed with the change from the M41 to the M46 and again when the change to the P type. Early 70's for the M41 to 46, 85 or 86 when they went to the P type in some 700's, then fully when they dropped the M47.

Planetary gear swap. Most likely no. The reason I say most likely is that I have no P type in front of me so cannot compare the two for size. And since the J type gears are no longer available, and the P type are, that tends to point to a difference between the gears.

Since many parts between the two types are the same or similar a side by side comparision would be the only determinator.

The differences that matter are the depth from front to rear, circumference at the outer edge for clearance inside the cone clutch, gear interface and the sun gear attachment to the cone clutch.

Front to rear depth affects travel and the actuating pistons ability to apply correct pressures.
Outer circumference self evident.
Gear interface self evident.

The sun gear is what has the splines that ride on the trans shaft. It has six(?) "ridges" that mate with the internal surface of the cone clutch.

If the planetary gears and cage are the same, and the sun gear mount to the cone clutch the same, they may change. At this point only a side by side comparison would reveal the ablity to swap.

This is just a quick overview. Further investigation would be needed to fully determine the swapability. The only reason I mention the possibility is because someone noticed a PJ type OD on a 700 in a salvage yard and asked me about it. then your question just roused the possibility.

Duane