This whole conversion looks to me, to have been rather badly thought out and unnecessarily complicated.

I  would have thought that fitting a forward facing lever to original underlever pin (modified) would have been a far simpler solution. 

It would be necessary to lift the lever to depress the breechblock and open the action and cock the firing pin, and, after loading the lever would have to be depressed to close the breech.  

The original extractor would be operated in the way all Martini actions operate and without any levers or complex alteration.

With this particular action it would be necessary to retain the present lever/sear pin which would hold the parts in position during the assembled parts to be fitted into the action frame.

An accurately placed hole would have to be machined in the sidewalls of the action so that a lever/cocking pin could be pushed through the sidewall hole and push out the slave pin and allow a squared section of lever pin to engage in a matching squared hole in one of the two lever cams. A cap screw would be needed to secure the lever pin in position. Easily placed on the end of the lever pin
Harry