I started looking seriously at the side cover and realized the cover is actually tapered at the the front.  The reason for it is obvious to me now, the integrity of the frame would be compromised without it.  Not having a gun in hand I did not see the angle, but now that I know it's there, I see it in many of the pictures!    It was impossible to measure in the pictures so I ended up just winging it.  The first picture shows several test angles, they are 20, 25 and 30 degrees.  I choose 25, the center one, it should give plenty of meat for safety.  The side cover is also "keyed" into the frame.  That can also be seen here, the double lines lay this out.

The second picture, because of the discovery of the angled cover, all my measurements were off by that amount.  I ended up redrawing everything.....was not much fun!  Just behind the front panel radius, there is a verticle layout line that indicates where the angle should end up at full depth, I'm told the math is never wrong, we will see.  Everything behind this line is gun lock stuff and cover screw locations.  The other long vertical line is the cover "key" line.  If you want to get dizzy study the drawing behind the frame!   It's the redone one.

3, is just a close up of the lock and panel area layout.  I did this to check that all my numbers.. "math again".. are correct and work on the actual frame.

4, The rough cover ready to get fitted.

I'm thinking this should get moved to Gunsmithing, if a moderator thinks it would be appropriate.  When I started the thread, I was looking for collectors to see if I could get some information and didn't know if I would ever get going on it. 
Bob

These next 3 photo shows the completed mortise.  In photo 5 there was still a small section to be removed from the bottom, up against the angled side.  

I setup the gun frame in the vice to finish the bottom of the mortise to final depth, and connecting the bottom to the angled side.  This was done by carefully lower the cut and moving forward  into the angle. 

4 and 5. By using the angle gage I made, I machined one side of the cover to see how good of a fit I would get.  By using the same gage to machine both the frame and the cover angles, in theory they should match and it appears they do fairly well.

Bob

Don't think it turned out too bad.

You're a master of understatement, Bob; I can barely see the join line and that's mostly because I know where it should be.

Bill Lawrence

This next photo shows beginning of machining the bottom of the frame...which is on top as shown here.   

The second shows the bottom completed, completed on the rotary table.

Third is a clearer picture of the frame and what has been completed.  I still need the top end waste, so the upper tang will be machined out in a few days which will remove the waste material.

Fourth, I drilled and reamed the lever pivot hole and machined the radius around the hole.  I originally was going the make this hole 3/16 (.1875) but decided to make it a bit smaller at .156 after studying the original pictures.
Bob

This thing is moving along faster than I anticipated.  Going to need to make some decisions on what caliber I want it to be, because I'm close to needing a barrel.  Either a 22 long rifle or 25-20ss (I have brass) would be easy.  It has a small 3/4 inch barrel shank, so that is a limiting factor.  I've had an interest, for quite sometime, in a 22-15-60 but have the obvious concerns.  I actually have 20 loaded original UMC rounds which I would not use, but because I have them, I think is why I have an interest in the cartridge.
Anyone have thought on this?
Bob

In this first photo I'm chopping out the space for the lever and extractor.

In the second, just cleaning up the back side of the pellet box (not a pellet box on this gun).  I just machined it down close to the frame because the back of the frame needs to be fully radiused anyway, which will remove most of the material I left.

The third is showing where I'm currently at in the build and what it looks like.

So here is the breech block.  The flat face machine marks will be polished before fitting the barrel.  These picture make those tool tracks look lots worse than they are.  Everything is done except the pin hole.

The second photo is the breech block fitted in the frame showing the alignment required for proper lever function and space for the extractor.

Last is showing the pin boring complete, with the threaded end showing.