Can it be done, lots of plain Stevens 44 around, CPA rifles has Stevens 44-1/2 Double set tangs, which i believe will fit a Stevens 44 Stock , as far as i can tell, Stevens 44 and 44-!/2 use the same stock, right? I have a small milling machine(Westbury) and skill to use it.Throughts?

J. pickup,

Some of the higher grade 44's were factory shipped with the removable double set trigger lower tang.

Since the original lower tang was cast integral with the standard grade 44 receiver, this necessitated milling out the integral tang and also would have been done before a standard 44 trigger screw hole was drilled in the frame.

The lower tang retaining screws - one long front screw and two short rear screws - are positioned fore and aft of your existing 44 trigger screw hole. 

You should be able to plug your existing trigger screw hole(s) easy enough, then carefully spot, drill, countersink for the heads and tap the new holes for your new lower tang screws as well. And you'll need to slot your 44 hammer to install a fly.

Where you may run into some head-scratching (though I suspect that Paul and Gail already have this doped out) is that the contours are different for the sear areas on the 44 and 44 1/2 hammers, so you may have to modify the 44 1/2 set trigger sear contained in your lower tang assembly to align and operate properly with your earlier 44 hammer. 

It was done before and there isn't any reason you shouldn't be able to duplicate the process. Just think it through and proceed cautiously.

Regards,
BP