Well, PFX and PF have near compatible yokes. The horizontal inductance is pretty close between the 2 so no issues there. The vertical inductance on the PF yokes is in the neighborhood of 12-14mH, whereas the PFX is around 7-8mH.
If you put the Tosh PF chassis on the PFX tube, you will likely not get full vertical size. The fix is pretty easy, see my mod thread here:
https://www.arcade-projects.com/threads/toshiba-tri-sync-pbxx-pdxx-pexx-notes-mods.21081/
Check out the 'Vertical Deflection' modification. You will need to change R323 from a ~1.0Ohm down to something around 0.750Ohm and that should give you more current in the vertical deflection and allow for full vertical size.