Hi Neil,
I found the same outcome as you. I didn’t want to reshape the new parts-it would have taken a lot to size down. I have reused my latches sleeve shoulder plunger. Replaced both springs for plunger and the latch spring and the latch adjustment screws.

I set the adjustment screws to where the face is just above the latch and the Cotter pin slides in. I’ve fired the main without issue about a half dozen times without issue. I may try to back each off screw another half turn and see what she does. Big help here as usual-reading through the thread you can see that-

Thanks fir your attention and remarks-much appreciated and I’m glad your results were similar to mine....so far!

Have Fun-bernie