Yes, les is absolutely right, it is not really worth modifying. The cranks are different also.
There were in-line 1275 A and A+ engines produced, the A series were to be found in midgets and marinas, whereas the A+ was put in the Morris Ital.
If you have a metro engine then it will be A+. If it is an A series transverse then it could be a mini or allegro.
Another distinguishing feature is the distributer. The A+ has a forked clamp with one bolt that holds the distributer in, whereas the A has an assembly that pinches the distributer with one bolt and is fixed to the block with another bolt.
The only way I know how to tell if the engine is unleaded is to remove the head and compress (or remove) a valve and look at the valve seat (where it normally touches the head), if there is a ring of different metal then it is unleaded if all the metal is the same then it is leaded, I'm not sure about engine numbers or dates that may tell you if it is unleaded, but generally after about 1989 it should be unleaded (I think!?!).
Cam.
