Different guns?

[hardlec]

I have asked before but not received much of an answer on:

Was it possible to shoehorn a 6 pounder into a Stuart? I would think a complete new turret would be needed, but even so, the next generation of light tank carried a 75mm, and by Korea the light tank had a 3 inch gun....

On a similar note: Could the British Churchill have carried a 25 pounder as its main gun?

 

[LeEnfield]

The Churchill was upgraded to a 17 pounder which would take out any German Tank. This is why the British brought in the Sherman Firefly tanks and which the Germans always tried to knock out first. The tanks with the 17 pounder tank could be recognized by the extra long barrel

 

[hardlec]

The Black Prince (17 pounder armed Churchill) had extensive modification. It would have been the I-tank for the Centurion as a cruiser (Centurion was the last cruiser tank.) WWII ended, and with it the need for an I-tank.
I am trying to learn if:
After Dunkirk, the UK ceases production of the 2 pounder and "skips" the 6 pounder, using the 25 pounder as a field gun and ATG until the 17 pounder comes into maturity. The UK puts the 25 pounder in the Churchill and then on the next generation of Cruiser, giving something the UK lacked through most of WWII: A tank with good firepower.