Yes to both but you will need to use the PJ lower spring bracket and bearing tube (the hoof is narrower) but the 7 bearings may fit
Top bearings are the same as far as I remember
The PJ spring is some 1 to 2 inches longer so it alters the angle of the bocks slightly but that dosen't cause any problems and you soon get used to the different style
If you are doing this on one set of bocks it should work OK but if you are changing the hoofs and keeping the 7 spring you may have to sand away a bit of spring on the bottom as the heavier 7 springs are slightly thicker (I think but it has been a while)
Jason