The 45-70 CMA rifle that I won at an auction showed up yesterday.  After the discussion about the quality of the kits. I was a bit worried.  My first impression is favorable, however.  The internals look just like original parts but may not be interchangeable.  I was unable to fully seat an original block.  The most obvious differences are the firing pin which is spring-loaded and removes from the front although the part that unscrews seems to be fairly tight and shows evidence of possible botched attempts to remove it.  I will have to make a custom spanner and try it.  The action is a bit taller by about 1/8" at the front.  It looks a bit strange.
The lever pin has no retaining screw and relies on the tension from the flat sprint to keep it in place.  This particular example is chambered in 45-70 with a #3 weight unmarked barrel.   
The tang sight that came with it is a POS as it will flow about a bit when raised.

I need to make up some BP loads next and try it out.  All in all I am not dissappointed as I only have $800 invested in it.

Jack

There is a spring.  I may have to put it in the mill and slightly enlarge the holes to give a sharp surface.

The bushing is an easy part to make, especially with your handy pattern! Many years ago I sent my high wall to Elwood Epps to have a 25 Epps barrel installed. The fine old German gunsmith who worked there bushed my fireing pin like this, with out even mentioning it or charging for it.

I made one of my CBE tools (crude but effective) and after carefully deepening the holes with a REALLY small endmill, I was able to unscrew it.  I will feel better now that I can make a replacement pin especially if I choose to sell this down the road.

Jack

In an earlier post and under another subject that spring is pretty much what I was referring too. 
I once owned a Laudensauck HiWall Winchester with the Neidner bushing conversion as was shared and it too used a similar spring as being shown to retract the firing pin. 
The assembly was actually unscrewed from the back as I believe his also were but I could also be wrong? 

Thanks for sharing Jack and when I bought my 12X37 Lathe. I never had any interest in even owning one.but the price was not one that I could down and didn't even know how to actually turn it on or to make it work. Ended up being the best money that I have ever spent. If anyone here is thinking about doing the same. I would highly recommend that you do it now and to not wait and I truly do believe that you will never regret it.