A. The needle bearing basically disintegrated on removal. 
b. Jug was a bugger but came off with patience,  and a shitton of soaking with a rust removal.
c. Look at the rings. This looks bad.

A. The needle bearing basically disintegrated on removal. 
b. Jug was a bugger but came off with patience,  and a shitton of soaking with a rust removal.
c. Look at the rings. This looks bad.

  

Do you have a photo of piston skirt?

Are you on about the shape of the top ring or what looks to be pitting ?
Do you know that they have keystone rings ?
If you notice , the top ring land is stepped 

  

I'll go snap a pic after supper. Original rings.  Dad did nothing but enjoy it til it didn't start the best anymore. Then he bought a different bike 

Here is the sleeve   

Hints of carbon.  No real pitting.  

Piston measures 69.72 
Jug 69.80
 

And .006 or 0.15mm side clearance 

It's a standard piston still.  Nothing looks inherently "bad".

Except maybe your measurements...  it's not easy at all to measure accurately even if you have a large micrometer and a dial bore gauge.

You really need to take the parts to an experienced machine shop with the correct tools and two stroke experience to measure the bore and piston.    The bore would have been just a hair over 70 mm when new...  Probably like 70.005 mm  Piston would have been 69.972 mm by the markings. 

Piston would wear smaller but bore would wear bigger. 

Easiest "home brew" way to measure is a feeler gauge up from the bottom in the center of the skirt...  It's not accurate, actual clearance measured by the book will be larger...  If you got a 0.006" feeler gauge in there your actual clearance would probably be 0.008" or 0.009".  Might run but would rattle like hell and might crack the piston.

Trivia:  Sometimes on an original engine like your there will be a faint ink stamp on the outside of the sleeve where it slides into the case...  normally would say something like "005".  That would mean your bore was originally 70.005 mm. 

 



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I live near the edge of the earth. Its a 100 miles to a town where this sort of thing may be done, it's possible it's more local but...I've searched and cannot find any such place even close by.... but I will keep looking!