I'm a little leery of actions that have been put together from parts then are no longer cased or blued...has it been anealed for polishing and engraving, perhaps?  I know that in the old days when Winchester had a receiver returned to them for rebarreling into one of the newer, more powerful calibers such as the .30-40 you desire, They would sometimes feel the need to reheat treat it before such a use.  I would have a qualified metallurgist check its hardness with a view toward rehardening it if needed. 

Incidentally, original case hardened actions are NOT as stong an action as factory original blued actions, quite the opposite appears to be the case.

BTW, if you would like to get rid of that lever droop, use a flat mainspring.  If you have a coil spring hammer, the FS doesn't touch it, but still bears on the proper surface of a flat spring lever to keep it in place.  The coil spring still operates the hammer (it is still the "main"spring.)

Last, but perhaps most important, you will want a SMALL, late style firing pin in your breechblock.  This was developed specifically for the higher pressures of the later rounds such as your .30-40.  If you are having to bush the block from RF to CF, this should present no problem fo you, just be aware of it.  Some would even counsel in favor of the Mann-Niedner conversion, but I personally think that would be overkill.

Frank, with the additional information, I would reiterate what I said about getting the hardness tested...there's probably a facility to do that somewhere in your town, such as the community college's metal lab here in my town.  If I were going to go with anything other than .22 long rifle or some very mild pistol caliber, I would be uneasy without knowing what I was dealing with.    Ditto the firing pin bushing.  I would not trust even the old large diameter BP firing pin with that .30-40.

Which schuetzen lever do you have?  Does it have the little bump in the middle of the front for the plunger to bear against or the ridge all the way across the front for the mainspring to contact?  If the latter, you can follow my spring suggestion, if the former, it will be necessary to rig some kind of spring or other device to put down pressure in front of the axis of the lever pin.  I personally would go with the flat mainspring solution myself.  

It looks like you are to the point many of us have reached at one time or another...the project has reached the point where it is time to do something and you want to get some bang for your buck.  Keep us posted and let me know if I can be of further help.  

Regards,
Froggie

Green Frog, you mentioned getting the action hardness tested. Where should the testing on the action be done and what rockwell hardness scale and numbers should I be looking for.