OK so I need some info, I'm in the process of putting a 13b with a 225mm flywheel and clutch in a 74 rx4 with its factory 4 speed.
Now the problem is, it seems the pressure plate is hitting the bell housing.
I can turn the motor by hand then it hits and locks down, I can turn it back the other way and same thing.
So is it not possible to use a 225mm clutch with the factory 4 speed?

 

It should work. I have a factory 74 REPU 4 speed in a rotary MG Midget with a 225mm pressure plate and it fits perfectly.

 

I'm using an act clutch and pressure plate. But the pursue plate is definitely hitting something in the bell housing, it will only let the engine turn half a rotation by hand. I'm going to pull it back out for the 3rd time now and see if I can find where it's hitting, I'll let you know what I see, this just sucks.

 

Fixed it. On the top of the bell housing right in front of the clutch fork on the inside. There's a little hump that I had to trim down with my angle grinder. Now it turns freely.