Marauder caliber change

[Argat]

Hello everyone I have changed my marauder from .177 to .22 without much trouble. I love the idea of interchangeable caliber but I would like to venture further. Changing marauder to .25 I know I could buy another but really like trinkering making gun shoot correctly. My .177 is shooting great and when I change it to .22 can't be any better shooting airgun.

So that being said what are all the parts I would need to change it to .25? 
I would appreciate any input that you could give.

 

[John "spysir" Blount]

All the same parts as from .22 to .177 + a new receiver.
So, bolt, barrel, clip/tray and for .25 add a new breech.
John

 

[T3PRanch]

Valve as well as breech block, bolt and barrel. I believe the transfer port needs to be reworked as well. Not cost effective. Crosman has the Parts Diagram available for download. Just compare part numbers between the drawings.
All the numbers below are Generation II.

BP1764 .177
BP2264 .22
BP2564 .25

Each drawing will also have either W or S at the end of the part # for Wood or Synthetic stock

Thurmond