Ouch... this doesn't sound good. Sorry... been busy with everything BUT engine work for a couple months. …. I finally got the spark-plug out of mine. 3-4 months soaking/heating/penetrating oil, and it still took 250 Ft-lbs to break free.
Next - push the piston with grease and see if my internals are similar to yours.
Regarding the cam - what did you end up doing? Some small parts like that could be built up with spray weld and reground.
Regarding the valve - what are the diameters of the stem and head? (mine are no where near out yet....)
hopefully the stem is a standard size, so if you can find one the right length, it can be cut/ground to work.
** just saw the prior post about using Model T valves.... That's an idea.